Just to clarify, when I said “*all* the rules” I meant all the ones in the ‘BuddyPress Pages’ block. Unfortunately it means I have to let all the users see all members, which I was trying to avoid.
I had this issue. I am using WPMU’s membership plugin. I was using membership plugin negative rules to block some stuff, but if I removed *all* the rules from the appropriate access level then I could see the first post again.