Collider falling off game object

I feel as though this question has been asked a few times although I haven’t quite been satisfied with the other answers. This issue seems kind of rudimentary so I don’t know why it’s not working and I’m sure I’ll feel stupid in the end.

Simply my box collider is falling off of a simple cube and I don’t know why.

The object is marked as static.
Untick the static checkmark and it should work fine.

What I think I see is the outline of a collider that has properly responded to gravity, with one end on a board and the other on the ground.

Is the mesh left floating on a different game object?