Not sure why, but I wouldn’t get any tank movement unless the impulse strength was set to an insanely large number well over one million. I found that ticking the Impulse Vel Change box on the Impulse panel of the blueprint made it so that reasonable numbers such as 2000 would move the tank.
That option makes the impulse ignore the recipient’s mass so more massive objects and less massive objects would no longer respond differently to the impulse. That’s fine for the Battle Tank project since the tanks all have the same mass, but may not be what you want if you have pawns or vehicles with different masses.