I’ve recently run into this too – it appears this can happen under some circumstances.
There’s a manual fix described in this thread:
short version:
- Execute the
Plex SQLiteapp (in the app folder) in the command prompt (power shell, terminal…) - enter
.open "<path to database>", pointing to the thecom.plexapp.plugins.library.dbfile in the server data directory (->Library>Plex Media Server>Plug-in Support>Databases) - enter
Delete from Tags where Tags.tag="<name of the tag>" and Tags.tag_type=11;and pressreturn - reload the web app to verify the tag is gone
- exit the command shell app by entering
.exitand pressingreturn