I have a similar question but I wonder if my issue is the same kind of solution.
I built a mesh gazebo, shown in my picture. I put some "jump and play" prims so they could jump on the steps and on the top level, at least partially. But they seem to like to "hide" in the one column. Would placing a normal "hidden" prim inside the column stop this? I would presume the physics of the column should be enough to stop it but it doesn't seem to. (The physics of each column are a simple "block" column to keep the LI down on the overall build.)