I have the same problem. filament makes it into the toolhead, does a little tiny push like always and then retracts. Manually loading works fine. It started after a cogged extruder. (Accidently closed the door doing pla and got heat creep). I have tried everything. No success. I am starting to think it may be the sensor on the feed that detects the cutter arm and low filament. I ordered new ones but am at my witts end. Nothing it stuck, nothing is jammed. On fresh boot, the feed and unfeed buttons work but once you get the error loading the ams (any slot) it locks out the feed and retract buttons. It gives no error except for “can’t load” I sure wouldnt mind a solution to this.
Sometimes the spring on Buffer at the rear gets dislodged and the slide can’t fully extend. The spring flicks back into place easily.