I’ve posted this over two years ago and never got any help and it’s still an on-going issue. It was an issue for a long time even prior to my original post 2+ years ago so this is a persist problem regardless of what PMS version I”m using.
I’m sure that like most PMS owners we have a certain level of particularness when it comes to how our files are displayed and I have the added curse of moderate OCD. As such I have gone through my library of nearly 6000 movies and have altered/adjusted tags and changed the posters to what I want them to be. However, periodically I come back and they’re all changed again. I just noticed the tags were being changed as well. This is infuriating to see all my work washed away like that.
I have “scan my library automatically,” “run a partial scan when changes are detected,” and “scan my library periodically,” all turned off and I only run a scan manually when I add new content (which is daily). I get that when I manually ask it to scan it’s going to look at all my files but is there some way to stop it from making changes I don’t need changed? It should only look to new (or newly modified files) to update/load to the server and not change the meta/posters on the existing files.
If this isn’t available now is this something you can consider adding - that the scan will only look for or alter/update information on newly discovered items?
Server Version#: 4.157.0
I am using a Windows 10 OS
The posters changing definitely comes up regularly - and I’ve experienced it myself even on proven “locked” posters. There’s definitely something that happens from Plex occasionally that changes data even when locked - that’s a whole other thing not going to get into because it never goes anywhere (which is kinduva answer in it’s own way).
You already have the automatic refresh settings off - specifically the “partial scan” one which I’d been recommended by a rep to turn off.
If you know which posters\data changed you can grab the XML from those titles and I think it can help identify the nature of the change; or at least the timing. There are reference numbers in the GUIDs for the fields\art that are sequential and seeing them flip once locked will prove they changed. One of the reps can probably give you more specifics for what will be useful for that troubleshooting, but if you can track down a couple titles that you know changed and grab the XML for them that’ll probably help.
With that in mind, I’d suggest grabbing server logs and they’ll also want to confirm your file naming structure (if it’s anything but the “right way” prepare to have your report ignored). At the very least, including that info now will help avoid some back and forth. 
Sorry I don’t have better info for you but that’s my advice anyways.
Personally I wish Plex offered an option similar to Emby\Jellyfin where you can manually lock all title data or prevent refreshes in different ways (one I like is no data refreshes for titles after 3 days and only if fields are empty - lets you still get episode titles\summaries without episode order changes on older titles messing with things). Very useful features to avoid this problem that comes up regularly no matter how many times Plex reps refute it.
