I lost a part of my temple because instance is bugged

I played with my friend in party in a temple and he crash when we played and try to reconnect and all is good. At this moment nothing happen but when i complete the temple and i go out, i can place some many room and enter in a new temple. I loot a medaillon so i decide to go out again and put this medaillon. When i come back my temple is back like when i played with my friend and i lost my room... I record this so pls explain how it's possible ?? https://www.youtube.com/watch?v=VTLxQJIar3k

Update ! My temple is still here but i can't join the new temple and i still connect to my old temple i don't understand but i lose nothing.