Hi all
I am only able to get 20 out of the 21 skulls needed.
Its not like I don't know where they should be, and I have collected all 21, but it didn't count the last one.
So now I'm stuck at 20, and I don't know how to get the last one.
I have visited all of the locations, so it is not like I have missed one.

Have anybody else experienced this?

Does anybody have any suggestion to have I can complete this weeks challenge?