You're adjusting the angle of the object and not the angle of motion for bullet, this is always the same. Because you have 'set angle' enabled it will keep setting the angle to the angle of motion.
The only way I can see to get this to work (so the rectangle continues the angle it had before stopped), was to use an instance variable (saving the angle on stop and loading it into bullet angle when resumed). Is this the best way to do this?