Setting cache: false seems to make the filter work all of the time.
Otherwise it prints out Filter Error: No TVDb ID found for Maid for every show and says Collection Warning: No items found
When it works, it prints out a couple Convert Error: No TMDb ID Found for TVDb ID: 43713 errors (3 vs hundreds of TVDB ID errors) and properly builds the collection.
Its very odd that its talking about TVDB IDs, instead of TMDB ID mapping issues (which I'd expect for a few of them).