I think I’ve found the reason: someone has linked this wrong “show” Weber & Breitfuß (TV Series 2022- ) — The Movie Database (TMDB) to the IMDb listing of the actual show MA 2412 (TV Mini Series 1998–2022) - Episode list - IMDb
I’ve removed the link, but it may take a while until this has vanished from the Plex database.
Wait a few days, then repeat the Plex Dance.
