This waht a GUP does, update the clients that are there in its Group, So if the GUP is working , it would be updating the clients in its Group, for the rest of the clients that are not in the group, move them in this group where the GUP is functional , or Create a new GUP in that Group.
But unitil and uless the client receives new LU policy about the GUP , it will not take the update from the GUP,
So you have to copy the policy localy on the mahineor troubleshoot the commuincation problem.