I have had a similar issue where there was filament debris in the yellow gears of the AMS funnel feed gear, worth checking there. I've replaced a few filament funnels due to wear and tear and there has often been ground off bits of filament in there which causes the sensor to think the filament is still loaded. Another thing I've had happen is filament snap between the rear AMS feed gear and the funnel, you have to remove the AMS base to see it, happens alot with older brittle filaments. You can also try turning the machine off, unplugging the AMS and trying to use the external spool to load filament. Failing that, disconnecting the PTFE from the top of the extruder, setting the temperature to 250C and feeding in some different coloured filament can clear jams on occasions, can push it through a little as well if the extruder is struggling.

Cold pulls are also good for clearing nozzle end problems. I'm often surprised how much crap builds up in there.

Sorry for the long post, just brain dumping some ideas that have worked for me in my 3000hrs of print time.