When you are in prone or laying on your back position, If you click "Q" to roll to the left or "E" to roll to the right and click "right mouse button" during the animation your character cancels the roll and goes the other direction.

This happens when pressing "Q" or "E" when laying on your back, and ONLY happens with "Q" rolling left when prone

Tested with 3 different weapons and it happpens everytime.