@chazzerb just incase this helps here is a link to how to clear up the caches on your plex server. Its possible stopping the server, deleting the current cache, restarting and refreshing the metadata may fix the problem.
https://support.plex.tv/articles/202967376-clearing-plugin-channel-agent-http-caches
If not you could try and take a look at the plex dance procedure for the movies causing you problems.
The purpose of this is to remove all cached metadata and xml data for an item that Plex usually keeps. This helps when you want to “start from scratch” for particular item
move all files for the media item out of the directory your Library is looking at, so Plex will not “see” it anymore
scan the library library (to detect changes)
empty trash
clean bundles (in menu next to server name, when accessed under ‘More’)
double check naming schema and move files back
scan the library
Support articl…
Hope this helps you out.
