That Plex version is the web client that your server provides, not the actual server version. To find the version, don’t report the number found under Settings > Plex Web > General but instead go to Settings > SERVERNAME > Settings > General
I suspect you may have hit upon the issue caused by a fairly recent beta release of Plex, as documented and discussed here:
If so, read all the posts, as there are some good suggestions to try. Forguy in post 3 or so links to the article on how to restore backup, while Dokuro offers some things to try to fix this without a restore from backup. I think it may only work if you use local metadata, which it sounds like you don’t (but are interested in).
Plex will read some tags in mp4 containers, but for anything else you may need to use external metadata files, which it looks to me like Plex mostly currently uses image data (posters, background art), but not titles or descriptions.
