Problem with CB list and ACL

Hi Guys

I have an ACL structure that looks a bit like this:

registered (view access registered+commitee+board+member)
member (view access: commitee+board+member)
board (view access: board)
comitee (view access: commitee)

I have a matching group structure
registered
+-member
..|
..+-board
..|
..+-commitee


I have several users that are member of both a commitee and the board (and are members of course), they have a group assignment of 'board+commitee' (nothing else).

I've set up that some CB lists have settings of Access=Board

But when they go to see the list, they 'you are not authorized'???
If I change the access level to 'Member' they are authorized, which I think is even weirder.

No input on this, is it a bug?