Rigidbodys

HI everyone,

I got several rigidbodys (boxes / crates). I made a script that lets a sphere expand (increase the size of sphere relatively fast) I want to use it as kind of shield. If I use it first on the rigidbodys, all is fine, but if everything lies there for a few seconds, and I want to push it away again with the shield, nothing happens ( the rigidbodys dont move) just if I move around or move one of the rigidbodys it works again.

the shield is just a collider, if i attach a rigidbody it works, but the forces are unnaturally strong and it looks weird.

Any idea what is the problem?