I ran into a problem with my AMS today. Some Bambu ASA snapped and somehow during the course of retracting managed to flip up one of the magnets inside the internal hub. No idea how.
This meant the filament was getting blocked from going out. When I took it apart (which is a tedious process) I saw the magnet standing taller than the others. It was turned upward, not laying like the other three.
Reassembling the internal hub is a chore. The only way to keep the magnets in place is to use a stack of two other magnets on the top side of the shell to attract them. This pulls the guide magnets in and lets you get the PCB back onto them. Otherwise their own magnetism draws them toward each other and they jump out of the slots.