I Need Help With Multi Material Printing

[spegelius]

Ok the movements back and forth might just the thing that happens at the beginning of a multicolor print. PrusaSlicer adds a sequence to the beginning of the print where it loads each filament once and purges some stuff at the front of the bed, 'priming' each filament. Why the extruder moves back and forth might be just to form the tip properly, I?l have to check if my printer does that too.

But the fact that there's no filament coming out of the nozzle indicates that there's an issue with feeding the filament all the way to the nozzle. The tip of the filament on the video looks kinda bad, can you test with filament that has the tip properly cut? Also after this kind of failed load, does the filament seem like the extruder gear has grinded it?

Edit: I sliced a multicolor model in PrusaSlicer and looking at the priming gcode doesn't show that kind of moving the filament in and out. I'd really like to have a look at the gcode file you are trying to print.