I have a "visitor" access level, along with many other access levels. Currently there are _no_ rules for any access level.
After upgrading to 18.104.22.168 when I go to any Buddypress page or the products page of Marketpress eCommerce while logged out (as a visitor) I get a "PROTECTED CONTENT" screen.
Disabling the plugin fixed access.
Downgrading to 22.214.171.124 fixed access.
One of my test user accounts had the same behavior. While still on 126.96.36.199 I was able to fix the user by going to /subscriptions/ and choosing another subscription. Oddly enough, that user didn't have an entry in wp_m_membership_relationship. I just checked again now and it does. Not sure if that was re-added when I downgraded or when I chose the new subscription.