During Co-op we had two cases in 2 different rounds where we had the event to stay in the circle until the time runs out.
Both times my partner described the game told him the event was a success.
The first time he then ran away and to me it looked like he was leaving the event which ended in a failure.
The 2nd time he stayed, but the chests only spawned after the time had run out on my end.
My logs: