New Files Not Appearing After Library Scan

The first movie I loaded, “…Thief”, works fine with the naming and structure as listed above:
…/Movies/To Catch a Thief (1955)/To Catch a Thief (1955).mkv/B1_t00.mkv
and also for the following structures:
…/Movies/To Catch a Thief (1955)/To Catch a Thief (1955).mkv (the actual movie file)
…/Movies/To Catch a Thief (1955)/B1_t00.mkv (but the poster is incorrect)

They even remember exactly where I left off the during the previous test, about 30 minutes into the movie.

Nothing works for any other movies - I tried your suggestion, and various combinations, each time being sure to do renaming outside of the Ples domain (Plex Dance), and “empty trash” before and after each file scan attempt. Nothing works.