If I go to the library and type "proverbs type:commentar" or "type:commentar proverbs," then all commentaries for proverbs will show; however, if I add the "y" to "commentary," such as type:commentary proverbs, then nothing shows. For some reason finishing the word negates the command.
I've tried the same search with several books of the Bible, and at least in the case of Acts, one volume, The Beginnings of Christianity, Part 1... will show with the "y" included, but nothing more.
I also tested with "type:c," type:co," type:com," etc..., and the command guesses from the "c" that the word will be "commentary" and pulls up all commentaries until you get to the "y" where the library returns 0 results.
I'm on IOS 13.3 and Logos Bible Study Tools 8.10.0.