I don't know if it's the same invisible floor/ciling you were seeing or not Endy.
This one eventually caused my bots to fire 1000 and 1000 right every cycle. That was strong enough to propel them far outside normal bounds, until the force extered on them to go back into the sim was the same as the force they exerted to leave it.
The result was a sort of equilibrium point they drifted back to if you moved them.
