New URL Group not properly restricting access

Over at our site we've been using URL groups to restrict access to a couple "members only" subdomains on our network for some time now.

In my attempts today (both before AND after upgrading to 3.1 of membership) to add a NEW URL group for another members only blog, I am running into a brick wall as far as getting it to work properly.

I have (to the BEST of my knowledge) cloned the settings from the URL groups and blogs that *ARE* properly being restricted to this new set, but non-logged in users and "Stranger level" users are still able to hit the subdomain.

To answer a few obvious questions:
-New blog NOT using default permalinks
-"Stranger level" access level DOES include the new URL Group in "Negative Rules"
- the new URL Group is configured identically to the working ones, simply with the NEW domain.

I would greatly appreciate any help and assistance getting this sorted out, it's a very odd problem indeed, and there is seemingly no "Duh!" fix I can see on our end.

Due to privacy concerns, I won't share the subdomain here publicly, but if a WPMU staffer needs it, please email me --> tyler AT middleearthnetwork DOT com