I don't know if others have the same problem like me.
We are able to make the skull puzzle all 30 minutes, right?
At my last look the chamber says: -3 minutes, x seconds left till next try.
Heeey, I can try again I thought and wanted to make it. Buuuuut: wait a little bit and then it says: 29 minutes, x seconds left to next ty.
It seems that I can make the skull puzzle only once per hour. :(