Physics is broken when loading 3D scene from another scene

I have a little game stump that I am attempting to develop. I have a well fleshed-out player controller. However, when I test the testing scene directly from the editor, it works fine. Yet, when I test the testing scene from playing the main menu scene and loading the testing scene from there, the physics is totally broken. Rigidbodies don't fall, and my player character doesn't move. The moving/sprinting bobbing effects work, but the character still does not physically move.

Any obvious...

Physics is broken when loading 3D scene from another scene