I have traded with my villagers to get them to Apprentice level and next in game day they have reset themselves to Novice.  I have tried 3 times and each time their level of progress has reset. Only the librarians seem to be affected by this bug.  My other villagers are ok.

Still having an issue with the Librarian villagers.  I leveled up 2 villagers to master level, their initial trade is bookshelves.  I also leveled up about 4 to Journeyman.  Logged off yesterday evening, 10/15/24.  I logged in this morning, 10/15/24, and one of the Bookshelf Librarians was back to Apprentice along with a few of the others that I had leveled up to Journeymen.  It seems that this occurs when I log off the game and later log back on.  All other villagers are working fine with keeping their highest trade level.