Issue granting permission to create spaces

I have a group called "Consultants" and I have given members of this group the permission "Create Space Content".

I have a space called "Clients" who inherit members from the consultants group. Inherited members get the permissions of the consultants group.

Steps to reproduce:

- Log in as admin and create a new user.
- Add this user to the "Consultants" group.
- Log in as the consultant user and try to add a space.

Members of the Consultants group can see the button "Create Subspace" under the "Clients" group in the sitemap (see screen shot 1) but when they click it, I get an ajax permission denied error (see second screen shot).

UPDATE

It seems that the consultant has to subscribe to the group - which I guess makes this more of a user experience issue. Surely adding a user to a group should also subscribe them to the group?