So I have tried allowing the bullet bounce to be on, as well as a bunch of other things, but my bullet still falls through the ground when it either stops or is going very fast.
The point of the game is to swipe across the cactus it turns his bullet on, and will launch him through the air. when he hits the ground, i set his angle to self.angle * -1, essentially making him bounce. He has a ground sprite that follows his x position at all times so he will always hit it, but sometimes if you swipe hard enough, and he's going fast enough, he hits the ground, and flies downward and back instead of bouncing back up. Ground is set on event 9, and bounce is checked on event 10.