OK, solved the problem by myself (Bambu Lab Support is still AWOL)
Deleting the app and reinstalling had not helped before. But this time I found the Configuration folder (Bambu Studio has a “Show Configuration Folder” under the Help menu), deleted the folder and then deleted the app. Reinstalled, configured the printer from zero, forced it to synchronize filaments from AMS (otherwise the app would not “see” that I had AMS ???), and that was it.
Thanks to the couple of people who reached out (not to Bambu Lab Support, who ignored my ticket).