Claim granted to other player but still no access

[Conquest of Blocks]

I have two players of which one created a group. Now he tried to allow access to his claim to another player which also joined his group. Even though he tried to give access to the whole group as well as to the single player and it said "access granted" in the chat window, the other player still can't neither modify blocks nor interact with stuff.

 

EDIT: After the claim was deleted and redone, it worked. But deleting and redoing the claims everytime a new member joins is not something that people would like, i guess.