Problem with Membership 2 Pro failing to assign custom user role

I’ve installed the Membership 2 plugin on thedigitalmosaic.com (a multisite, multinetwork build). The build has several custom user roles – Storyteller as one example. I wish to assign role(s) upon membership subscription, and have set Membership 2 to do so (giving the Storyteller role when one joins as a Storyteller member, for example) but the specified user role is NOT assigned upon successful registration.

Join page is currently omitted from nav, but can be reached at

http://thedigitalmosaic.com/register

I’ve tried switching off plugins, reverting to default theme, all to no avail. Thoughts?

I can provide admin account/pwd if needed for troubleshooting. Thanks in advance for your assistance.