How would I return a simplistic floating platform to a flat orientation?

I have an ice platform “floating” on flat water. It’s intended to behave quite simplistically and predictably; it never changes location, but tilts when one or more physics objects stand on it. Resists tilting too far, and returns to flat when nothing is on it any more.

However, whether I’ve tried using a physics constraint with limits or blueprints code that adds rotational force, dropping a cube on the platform causes it to tilt as far as it likes and never even attempt to return. I have observed no difference in anything I have done, except when using print debug commands.

Here’s a pic of after the cube has fallen off. The rotation is staying the same. (I know the force has the values in the wrong slots, but I can solve that after I get the platform to show any kind of movement.)

The (current) blueprint code is here (Again, I know I’m not using the delta yet, but I can deal with that once I get any movement at all):

What could be going wrong, such that it ignores all attempts to limit rotation or re-orient after tilting?