How to create iTunes smart playlist of playlists

I'm using iTunes 12.5.3 on Windows 10. I am trying to create a smart playlist that selects songs from other playlists, limited by storage. (Much like in https://apple.stackexchange.com/questions/74118/how-do-i-configure-a-smart-playlist-to-show-songs-not-in-other-playlists) I have a number of these lists already, which I created several years ago, with a previous version of iTunes. My problem now is that I am unable to select any particular playlist in the smart playlist dialog. The playlist name is defaulted to "Music", as shown here: Further, if I open one of my existing examples, the dialog will show the playlist(s) I'm harvesting, but _won't let me edit the playlist names_. What is going on here? How can I fix things so this works? I know that an alternative solution is recreate the rules that form the source playlists in a new smart playlist, with the additional size restriction. This is what I'm now doing as a work-around, but it would be preferable to just get the feature working like it once did.