Plex Server will not display TV shows with this in title s01e01, etc

Server Version#: 1.20.3.3437
Player Version#:
I am running PlexServer on a Synology DM418play. I was adding some text to a show for my wife making it easier to list like the common S01E01, S01E02 (season 1 episode x) but they would not show up from either a PC player or Firestick on a tv. I tried moving the files around, coping pasting, back in and out, etc. I could see them in a folder view from a pc but not the Plex player view (and they played fine). At first I thought it might be because there were space in all the words in the title. I stumbled on the fact that if I removed S01E01 it would show back up in the plex player. I went back and forth a few times. add in S01E01 with no other changes, it disappeared, add it back, reappeared.

is this a bug or a design to disallow the naming convention like that? Ironically I went with 1x1, 1x3, etc… to convey the same info and it works just fine. I will not show me a title if it has S01E01 in it. Anybody else see this issue?

P.S. I see other post like this…and I did the Plex Dance with no luck. It isnt the end of the world as ill just use 1x1 instead of S01E01 now, but seems very odd that it behaves this way.

Thank you for that. However, that is exactly how I named it and it disappears. But same folder if I put 1x1 instead of S01E01 it will reappear with nothing else changed. Though, i do not have this in a discrete TV folder but a folder I named after my wife since it is a collection of all of her movies and shows. Everything else show and works just fine in that folder (streaming to various devices) the ONLY issue is if try to put the S01 type designation in the name. Anything else I have named them or other numbers or convention shows just fine. It is like Plex has a filter explicitly against showing a at title with S01E01.

Name that worked:
Mysteries 1x2 Deadly Estate.mp4

Name that disappears in plex player view:
Mysteries S01E02 Deadly Estate.mp4

Ok, but it is ONLY ignoring it with that naming? other than that it works just fine? so why would it display, stream, show just fine any other way? or is the point the S01 naming convention is designed for the Plex TV folder only? I am trying to keep it simple for her so may just not bother with S01 and do the 1x1 type thing then she has them all together. just seems odd. Ill try sub folders with TV designation and see if that changes the behavior.

Thanks Ninja,
surprisingly in running a plex server(on my NAS) for last 3 years, I had never encountered this before. I appreciate your guidance. I created some new folders and designated them TV and Movie for her. That did solve this and a couple other small things. I still find it interesting that using the S01E01 (etc) in the name under a movie folder will completely hide it from showing, as opposed to just listing it but not making any attempt to order it properly (like it does with a same name tv episode but with 1x1 or anything else in the title) but minor issue, now that I understand the mechanics behind the two folders. I never realized there was actually some programmatic differences between the two beyond just naming.

Thanks again!