Welcome to the result of their V3 api change at tvdb… The list is ongoing and growing of things that dont work. However there is nothing you can do about it as Sonarr is reliant on tvdb and ONLY tvdb so you’re SOL bud until tvdb fixes everything yet again.
Such a great featureset (Sonarr) being bottlenecked and made to look broken so often because of the forced usage of tvdb but in all fairness it is by choice so…