It's more than broken, it's breaking my machines. I have hotends running wild or not running at all. They are flying off the back and front of the bed, slamming into each other stopping in the middle of a print and releasing all the filament back out of the top of the extruder. 4.9.1 really bit but 4.10 is horrible. Thank God I saved 4.8. it somewhat works decent. Back to the drawing board on that one. Holy cow.