Hey MADHOUSE,
After further investigation and discussion, we do not believe that this is a bug. Physics Simulation, although this may sound silly, is just a simulation. This means that it will not be perfectly replicated on the clients, which would explain the differences you’re seeing, especially when there is lag involved. Replicating physics perfectly is a tricky task that will require some additional work likely using a custom pawn.
I’d recommend taking a look at this thread for a bit more information as far as a starting point if this is something that you’re looking to do:
If you have any further questions, feel free to let me know.