Could it be the filament or slot (#3 slot) of the AMS? This filament is a heavy glitter pla, maybe it is causing too much friction in the AMS? This stuff prints pretty well on my p1p though it can have bed adhesion issues.
edit: loaded slot 3 with bambulabs filament and loaded/unloaded. Failed to unload on first try, the same issue as the other filament. Cut the filament at the back of the ams, seemed to be stuck in the filament buffer. After some wiggling it came loose. I haven’t had any issues with slots 1 and 2. Haven’t gotten to slot 4. Maybe this is only an issue with slot 3.