Open the web app https://app.plex.tv
Check all your Collections, if any are set to ‘Custom Ordering’ (edit, ‘Advanced’ tab) Reset that to either ‘date’ or ‘title’.
Check collections both in the tv show library(s) as well as in the movie library(s) – even if you already edited a same-named collection in the other library.
Then do this: Plex for Windows won't run - #3 by OttoKerner
Update to the newest player again.
