The knobs are supposed to be there but on G2 Onslaught and on Victoria on the strut is assembled incorrectly. Hotspot and onslaught have the Nubs in a place where they don't interfere with the knee locking gears. The backwards Nubs prevent the knee strut from going forward enough to lock it without breaking the toy.
The nubs on your pictures onslaught are the correct assembly.
