I’m on mobile right now so I can’t provide the logs inicially, let me know if you need them.
Yesterday I was playing the map as client and at the bridge after the first grim (the one that has to be lowered), we had one person lowering the bridge and the rest of us waiting with the sledge.
The host was in front of the sledge, pushing against the invisible wall. After the bridge crashes down it jumps up a bit again and I think it was at that moment the invisible wall vanished and he walked off the cliff, through the bridge and fell directly to his death.
My guess is that the invisible wall vanishes a fraction of a second before the floor of the bridge is in place and the “top” end of the bridge has no collision. I couldn’t test it but I guess jumping on the bridge would work but since he just walked he could pass through the narrow top of the bridge without touching the floor.