Platformer character sinks to hotspot?

I'm still new to CF2.5, so this is probably a n00b problem, but I couldn't find a solution in the tutorials.
I'm working on a basic platformer using the built-in physics engine, but my character (set to Physics - Platform Movement) sinks into the ground to where his hitbox's hotspot is.
The ground is a Physics - Background object, set as an obstacle.
I have an event set up to stop movement when Character's Hitbox collides with background objects.
I can set the character on the ground by putting his hitbox's hotspot at the bottom, but he still goes halfway into walls, and CF keeps saying physics objects need to have the hotspot at the center of gravity.
I've checked every fine detection thing I can find on both the character's hitbox (which is a separate object, with the character attached to it.) and the ground.
Anybody know why this is happening, and a way to fix it?

I set the hotspot back to the center of gravity, and now it seems to be working, even with collisions with walls. Hmm. Well this should work.