Server Version#: 1.19.5.3112
Player Version#: N/A
I - and others - are unable to manually analyze shows or movies to generate preview thumbnails.
I previously reported this issue here, and others have weighed in to confirm it remains an issue for them as well.
The issue seems to have become more pervasive than when previously reported – manual analyzing no longer generates previews for either movies or TV shows.
This has been an issue since the 1.19. series of PMS, the ONLY way I can get manual analysing to work is to shut down PMS and restart it, manual analyse will then work and also auto analyse new programs as and when added until the next nightly “Scheduled Task” and stops again, certainly does not do a library analyse during the Scheduled Task session.
I am running PMS on a Synology NAS and it was all working perfectly when on 1.18.5.2309 but both auto and manual analyse stopped when upgraded to 1.19.4 and still not working on 1.19.5.3112 as @amm350 has noted and nothing from Plex acknowledging this.
I also have this issue. Not generating when new items are added. If the server has been started recently you can force it by hitting analyze or using the command line scanner with force, eventually forcing it through command line or hitting analyze doesn’t trigger it. Once I restart the server again and try it again through command line or analyze it will run, but it will not run when media is added or during scheduled tasks. Running on ubuntu server. 1.20.0.3133
I’ve tried toggling media index file creation on the library on and off, and resetting the scheduled tasks. Nothing really seems to help.
Video preview thumbnails usually generate correctly for me when adding media. I don’t think I’m badly affected by that part.
But when I’ve been messing with media, sometimes Analyze on an item won’t start thumbnail generation. I don’t see “Indexes: SD” in the info, and no other Scanner/Transcoder processes are active.
Restarting Plex usually does the trick for me. Or disabling Generate video preview thumbnails, saving, and re-enabling.
Mostly just wanted to put my hand up too.
Adding my +1, video preview thumbnails are not working reliably on 1.20.4.3517 either as a scheduled task or when media is added. I have to restart then manually kick off analysis to get them. I might roll back to an earlier version and see if they work after doing that.
Same here on 1.21.0.3616 - most of the time thumbnail generation isn’t working either automatically (on schedule or when media is added) or on a manual analyse. Turning thumbnail generation off and on again in the settings, followed by a manual analyse, seems to work, but at some time thereafter (not sure exactly how long, but less than a day it seems) it stops working again.
Just adding my name to the list seeing this issue.
ver 1.21.2.3943
Adding my +1 - experiencing the same thing. Been happening for months now
+1
Using latest. version: 1.22.3.4523
Analyze doesn’t trigger video preview thumbnails… and restarting doesn’t really solve it either.
Restarting followed immediately by analysing seems to trigger it for me (at the library or episode level - analysing at the series level doesn’t work), but as with turning it off and on again in the settings, it stops working again an indeterminate amount of time later.
Has anyone managed to figure out what specific event is causing it to stop working?
@ChuckPa - Here’s another one.
Engineering is aware.
I’ve not been able to follow up with anyone today.
I have been dealing with Synology issues
Thanks Chuck - just wanted to make sure the team is aware that this is not an isolated issue specific to my environment - this is a repeated and reproducible issue across all platforms that has been occuring for almost a full year.
If it’s only you, and you’re not right in the head, based on other posters in this thread, It’s clear you’ll have companionship at the funny farm 
Right!
Thanks Chuck - I’ll check in with you next week - have a good weekend.
Adding in my voice that this is an issue on UnRAID using a Plex docker.
Thanks for the reply to this thread, @ChuckPa
Same issues here. Analyze has NEVER triggered thumbnail generation for me. (or chapter thumbnail generation). The only thing that works is:
After doing this, thumbnail and chapter generation will start.
BUT
it completely stops seemingly randomly and any new media added (even during scheduled maintenance hours" is ignored.
I recently added a TV series with 10 seasons and 760 episodes. It generated thumbnails for part of one season and then stopped. Maybe did 40 or 50 episodes total.
I’ve even tried changing my scheduled maintenance window to a full 24 hours and it made no difference.
This is SO maddeing … especially when this issue has been around for YEARS.
At the VERY LEAST, if you can’t figure out how to fix this,. add a button for us to manually generate preview and chapter thumbnails.
I’m on latest version, Version 1.23.1.4571
There is a button to manually generate preview and chapter thumbnails; it’s in the three-dot menu and it’s called “Analyse”. Unfortunately, when automatic thumbnail generation stops working, manual thumbnail generation also stops working, and a restart of Plex is necessary to start it working again.
The other unfortunate thing about Analyze is that it only seems to work at an episode/movie level. You can’t Analyze a whole TV show and expect Plex to generate thumbnails (which is also a bug IMO.)
Yes, I’d noticed that. You either have to analyse each episode individually, or the entire library (which thankfully will only generate thumbnails for episodes that don’t already have them). The option is there at the series level, it just doesn’t work - so definitely a bug.
