I just started playing the SU-100. I'm frequently seeing this weird problem. Perhaps it occurs in other TDs too, but I never noticed it in the previous TD in the tree (SU-85).
I jump into sniper mode, and take a shot
I come out of sniper mode to move forward or backwards, but the turret then goes nuts and points to the ground.
Now, the movement controls will not work and I'm stuck. I have to stop touching the screen, wait a second or two, and then I can engage the movement controls again. All the while, I'm a sitting duck. This makes peek-a-boom in this tank very risky.