Yes, Play History would be lost if files were removed from the Library.

Strange, I've not seen anything like this reported. If you can reproduce (make sure you have a copy of the database file) capture this in a debug log (step 4b) as that may show why it happens: https://www.mediamonkey.com/forum/viewtopic.php?f=7&t=69

http://mediamonkey.com/support/index.php?/Knowledgebase/Article/View/16/0/modifying-the-mediamonkey-db-and-ini-files

If you are suggesting that I deleted all 20k tracks from my database, I did not, and I'm sure I would remember doing so.

If I had done so, would not all of the play history and ratings for those tracks be gone as well? All of that meta-data remains in my database.

Sounds like the files were removed from the database (which would be a user action) and rescanned (Folder Monitoring could hide this).

When files are removed from the Library they're also removed from Playlists. AutoPlaylists will still work after files are rescanned as they're rule based, not file based.

I don't know why someone coalesced my bug report onto this thread, but these are different issues. My database is still there, and fine -- except it no longer contains any manually-created playlists.

Please read bug reports before lumping unrelated issues together, for everyone's sake.

I downloaded and installed 4.1.30.1914, and quite unfortunately, it has removed all the tracks from all my manually-created playlists. Auto-playlists survived. All of the manual playlists still exist, but they are now empty.

Library is about 20k tracks, on a Windows 10 desktop.