I’ve been using Plex for around a decade. I have used the Plex desktop client for Windows and Mac. The Plex HTPC client for Windows and Mac and the Xbox client.
None of them play specials inline with episodes.
So I get to the end of season 1 and the continue playing starts playing episode 1 of season 2.
If I go back to the homepage the continue watching will show the appropriate episode in specials.
Am I missing something or do all the clients that I use not support that functionality?
AFAIK Plex has always been like this - it’s not client specific, specials go into the Specials Season (0) at the beginning. You have to know before hand and manually go to the correct special if you want to watch them in order.
I don’t see any real easy fix for this since Plex is just ordering content based on the metadata source it’s using, and even on TMDB etc specials are listed as Season 0 or just Specials.
Maybe if Plex supported custom episode ordering, but you’d likely have to manually move episodes, or maybe create a new metadata agent? I hear that’s a thing now.
I suppose this is about a slightly different aspect.
If you watch an episode, Plex will add the next-aired episode to the Continue Watching hub. If there’s a special airing between two seasons, that special should be listed in Continue Watching once you finished the previous season (similarly for mid-season specials).
This wasn’t always reflected in the post-play screen (Up Next).
I recently started rewatching a show which started with a pilot that aired as a special 
… the show has more specials, but after watching the 1st one, Plex offered s01e01 in Up Next. Hence, I assume it’s supposed to work as described/expected in the new-experience apps.
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That’s not to dispute your point about displaying specials inline with their seasons. You could create a smart playlist/collection, sorted by episode air-date. There’s a feature suggestion asking to have such an option as a native Plex feature.
My experience with air-date specials queue up next automatically is that it’s hit or miss depending on how you’re playing the next episode. Either hitting the “go to next” button during playback, using the “Up Next” screen after an episode ends, or going back to the Home Screen and using the Continue Watching row. I feel like returning to the Continue Watching on Home Screen after an episode ends is the only time it works, but I’ve not bothered to sort out the inconsistency. I just know not to rely on it when I know there are specials that mix in with regular seasons via airdate.
As tom80H mentioned, Up Next didn’t always reflect it.
Recently had experience where I reached end of season 01 episodes after hitting “next” or using the “up next” screen each time and when I went back to Home Screen, Continue Watching jumped to Season 00 Ep 5; skipping 4 other unwatched episodes in S00. It pulled the next air date episode after S01 which was S00E5, but skipped the first 4 that had earlier air dates and should’ve been interspersed with the S01 episodes if it was going by air date. I picked S00E1 and started from there and it played the specials in order.
This is all Roku experience which has more caching than other clients so it can be less dynamic so it might need that refresh from returning to the Home Screen to trigger inserting an episode by airdate. That’s just my theory. 
TVDB has some fields to choose where to place specials in-line with regular episodes (Airs After/Before Season & Airs Before Episode). Jellyfin uses it, and it seems pretty simple.
There’s also a field ‘Critical for Show’s Storyline.’ That could be useful so that non-critical specials aren’t included in autoplay.
I think something that would help with this situation would be Plex finishing the build for the TMDB Episode Group feature. Jellyfin handles flipping TMDB Episode Groups really well and I’ve found it’s more seamless than flipping between TVDB\TMDB order. Emby is working to support it as well (it’s “moving up the list”).
Episode Groups can be setup to include specials inline and are more flexible to create than TVDBs DVD\Absolute options which are kinda cumbersome to setup and manage there.
It’s been my experience that specials always play in-line with normal episodes. As long as your show is marked as “UNWATCHED”, when you select “play” on the show (not S01E01). If you then rely on resuming your show watch via the “Continue Watching” menu, it always seems to queue up specials for me based on when they aired. Even the “Up Next” picks the specials when I start it properly from “Continue Watching”. Gravity Falls has a handful of specials, and it actually kinda breaks the flow when I allow it to play all of them that I got.
Clients I use:
Primarilly, Plex for Windows.
Less often, Nvidia Shield. (Don’t know how consistent this client is, it’s a family member that uses it, but I believe it picks the specials automatically)
I think the issue that might break the sequence is if you do not mark a show as “Unwatched” when you watch it again. If you just select an episode (S01E01) and play, it then seems to go in order, ignoring specials. This has come up when my family member who loves to rewatch a show doesn’t unmark a show, so it no longer follows aired date and jsut goes numerically.
It a new show I’m watching. It has never been watched in Plex at all so that’s not a factor in this case.
Plex has never played a special when the special air date falls between two normal episodes in any clients I’ve ever used.
Works for me with the new experience apps.
I just completed re-watching s01 of the show I’ve mentioned above and instead of listing s02e01, Up Next is listing the special aired before s02.
s00e05 → s01e01 → … → s01e13 → s00e06 → s02e01
I just did similar with Roku New Experience and the Up Next never offered the specials that were in air-date order. I finished the season and it then offered the next air-date episode in Up Next and Continue Watching but skipped the 4 unwatched specials that shoulda been offered up earlier. I had to manually start from S00E01 to reset it.
S01E07→…→S01E12→S00E05 skipping 4 episodes that aired between the last few S01 episodes (they were specials included on the DVDs that added “extra scenes” for those episodes).
So it’s definitely an inconsistent experience. I know Plex does it but I also know not to count on it to work. As I said, it might be a Roku specific issue and I wouldn’t be surprised if that were the case because it’s a less dynamic client.
It wasn’t that big a deal but just pointing out there’s definitely inconsistency of experience.
Edit: For this particular show I ended up redoing it using TVDB DVD order to force a specific order. It was kinduva a mess already (Girls und Panzer).
Off topic: have you considered adding those as extras for the corresponding episodes (deleted scenes)?
In this case they are kinda odd - anime gets funny sometimes and this series particularly so as it’s a mix of one TV season and then a bunch of OVA and movie releases.
These specific OVA episodes were produced specifically to act as additional scenes for the original episodes (though none are critical). They coulda been done as extras but they didn’t really fit, and I had hoped it’d work out to play in air-date order… it just didn’t.
Also, for my household folks are used to looking at Specials instead of Extras because I put explanations and context in the Summary Details for the season to help sort it out. That’s harder to do with Extras (particularly if ordering them is still kinda flaky - which was a long time ago but threw of my use of extras since it wasn’t fixed for a long time).
It wasn’t a big deal just an interesting example that happened to occur at the same time this topic posted is all. I learned long ago that Plex can play specials in aired order, but at least in my experience on Roku it hasn’t ever been consistent. It hasn’t come up enough for me to have dug into it or be concerned about it really. Probably not that terribly common for most folks so maybe with New Experience that might be something to check into.
Edit:
So just a few hours later had an experience with this situation. Got to the end of Jujutsu Kaisen S01E24 and Up Next showed S02E01 as the next episode. But I know there’s a Special S00E02 Jujutsu Kaisen 0 Movie in this series that’s actually next based on air date and viewing order. I’m not ready to watch that so I go back to the Home Screen and… S00E02 Jujutsu Kaisen 0 Movie is queued up for the Jujutsu Kaisen series on Continue Watching. So that fits with my experiences that Up Next on Roku doesn’t reliably pick up Air Date order but Continue Watching does… it’s a discrepancy. Hope this helps.
If only the new experience was rolled out everywhere… Still waiting on the Android TV update.
I’m waiting for the Plex for Windows update.
It’d help if it was consistent too. Particularly since that was one of the stated goals.
iOS device New Experience puts TV Specials last instead of first in season display. And on Roku New Experience, they have a show\season card mixed into the episode row.
In case it helps folks, particularly around anime and the bit off-topic chat between me and tom80H, I thought I’d just mention quick ways I’ve found to manage anime tv\movie organization.
Anime has a relatively unique situation where TV series and Movies and OVAs all go together. A simple example would be Sailor Moon Crystal where first 3 story arcs are season 1-3 and the last two story arcs and finale are 4 movies. So how do you put these together to keep track of them as a group?
The function I use most often is to use TVDB order. In most cases, for anime, TVDB will allow movies and OVA to be setup as Specials. This works for Sailor Moon Crystal. You get the first three seasons and then the movies are setup as specials and the aired order function will play them in order (which we’ve determined mostly works). Worst case, at least it’s all together under one listing.
Occasionally it can work better to use TVDB DVD or Absolute order where it sometimes breaks those specials out a bit differently.
TMDB will sometimes include OVA\Movies in Specials but lately they aren’t allowing it. They’re getting a bit more strict on episode order too and even with Episode Groups (which isn’t supported in Emby or Plex yet) you can’t mix\match TV and Movie titles.
The other way to go, particularly if you want to keep movies in the Movie library and shows in the Shows library (or avoid TVDB order) is to use collections with the same name. If you name a Movie library collection “Sailor Moon Collection” and a Show library collection “Sailor Moon Collection”, when you view one collection, it’ll show you the other collection from the other library too. Similar to a “related” row. It’s not ideal but it works to at least show you the associated titles consistently.
Lastly you can do as tom80H mentioned and include them as extras. This would work pretty well if you have a series that only has one or two additional OVA or Movie Titles.
Personally I mix and match depending on the situation. Macross and Gundam worked well using Collections while Girl und Panzer worked well with TVDB DVD Order. Anime organizing will always be odd\finnicky - even if you load a custom anime meta agent! - so since it was kinda related I thought I’d mention some alternatives here.
