I just had this happen to me twice. I fixed to today with taking a flat head screw driver and pushing the folded part of the seat belt, let’s say it is folded on the left side, to the left side cavity of the seat belt holder where it is a bigger space. Slowly to it took inch by inch as I forced it into that bigger space until the fold disappeared back into the seat belt holder. While use ding a flathead screw driver I also held the seat belt open so the fold got smaller and smaller as it retracted back into the car. Hopefully that helps