Membership Plugin: New Site Creation wp-signup.php Redirect Problem

Hello. I'm having an issue with the Membership plugin on a multisite setup. I have set up a subscription plan that gives users blog creation ability. However, when users with this subscription attempt to create a blog via the Wordpress Admin (My Sites > Create a New Site), Wordpress tries to take them to mydomain.com/wp-signup.php, which is redirected to mydomain.com/register (the Membership plugin's subscription registration page).

At that point, if the user clicks on "Sign Up" for the subscription plan, a message displays, telling them that they already have that subscription, and gives options for switching to a different subscription. So, they never are able to reach a page that allows them to create a blog. It seems that the Membership plugin is causing this redirect to happen.

Any idea why this redirect is happening, and how I can get blog creation to work?

Thanks in advance for your help!