I'm risking appearing insulting but I have had a devil of a time with the QIDI filament, both ABS and PLA, tangling on the spool during use. I've lost a number of lengthy prints when this happens. All kinds of rage does that engender. So... have you ever peeked over the back when this happens to check the condition of the spool feed. I've had mine also on occasion spring off the spool and wind around the spool post. That grinds everything to a halt QUICKLY. The QIDI filament is very poorly wound on the spools. You've probably already checked this and it also wouldn't explain why the jobs stop at the exact point each time but... I'm just sayin'. I've never had this occur with the Hatchbox filament that I also use. I don't plan on ordering QIDI filament when what I have now is gone.