WPMU Membership Plugin Error with BuddyPress Group

Hello there - having a strange issue with WPMU Membership which only started after we did the update to the plugin (which I think was yesterday).

On this site we have three access levels Visitors (strangers), Free (signed up but did not pay), and 0bservers (paying members). In the forum area, there are many public groups for everyone to use, but then we have one private group which only paying members could access and see. The group is called "Private 0bservers' Forum".

Yesterday we started getting message from people saying they could see updates to the private group even though they were not members and also even when they weren't even logged in at all (such as a Free access level).

When I did some testing, it was bizzare because when I was logged in and switching between the various access levels, everything seemed to work fine. Updates to the private group were hidden to everyone but the 0bserver level paying members.

However, I then logged out completely and checked and I could see updates to the private group.

Any thoughts on this?? As I said before it used to work perfectly before the update.

Thanks and regards,