Permissions with Membership plugin

I am having a bit of trouble getting Q&A and Membership working together.

I would like unauthenticated visitors to be able to read questions and answers, but NOT answer or comment. This is the Q&A VISITOR role that comes with the plugin.

People who join (for free) should be able to comment and answer as well, but NOT ask. I have assigned these permissions to the SUBSCRIBER role in the Q&A settings.

People who pay for monthly/yearly plan should be able to do the above AND ask their own questions. These permissions are set and assigned to the CONTRIBUTOR role in Q&A settings.

I have configured Membership as follows:
- three access levels (Q&A VISITOR, SUBSCRIBER, CONTRIBUTOR), each assigning each level to the above matching roles in the advanced section of the Membership Access Level edit screen.
- two subscription plans (1 month or 1 year). I have set prices and then dragged CONTRIBUTOR (set for 1 month or 1 year, with the appropriate price), to under "starting point". Under that, I have added the SUBSCRIBER level and set that to indefinite so that when the period of membership lapses, they revert to the lesser access.

However, I find that my test user who has a monthly membership, cannot access the ASK screen.

My admin role can see and access the ASK screen.

I hope that you can help me figure this out.