Hi Jason, thanks for the quick reply, I'll send you a PM containing a screenshot of the list of plugins we've installed. But I think I can help you with fixing this bug.
S2Member settings (on the Network Admin screen) has 3 options:
1)Disable Registration through wp-signup.php.
2)Allow Anyone to Register for an account (username) through wp-signup.php.
3)Allow anyone to Register for an account and Get a free blog through wp-signup.php.
Now go to the Main Site settings (mydomain.com/wp-admin/network/settings.php) as a network Admin
There are four options:
a)Registration is disabled.
b)User accounts may be registered.
c)Logged in users may register new sites.
d)Both sites and user accounts can be registered.
When I enable 1) and check my main site settings, I see a) enabled.
When I enable 2) and check my main site settings, I see b) enabled.
When I enable 3) and check my main site settings, I see d) enabled.
The option c) is never enabled on any of the plugin settings and I think this is the issue. The plugin is supposed to allow creation(registration) of new sites by logged in users (users who have "Purchased" a membership plan (username)) and restrict their creation of number of blogs based on the membership. I think it makes sense where the bug lies as option c) is never enabled.
Hope you solve this issue. Thank You.
Looks like there's already a member who has this bug:viewtopic.php?f=4&t=6370&p=14826
P.S - We have the exact requirement as this member (see ink above) has too.