The roles that have been added to the groups are not listed and group appears with no roles. When the user tries to add the same role again, it's still not listed but this message is shown: 

Role galaxy.test could not be assigned to group new_group.

 
The role is already assigned to this group.
 
standalone mode

branch:

https://github.com/ansible/ansible-hub-ui/tree/feature/rbac-roles

Steps to Reproduce

1- Create a new group

2- Create a new role

3- Go to the group from step 1 and click 'Add roles'

4- Select the role from step 2.

5- Click Next

6- Click Add

It's always reproducible

Actual Behavior
Role galaxy.test has been successfully added to new_group. message is shownThe screen is still empty with this text:

There are currently no roles assigned to this group.

Please add a role by using the button below.
 

Expected Behavior

Role galaxy.test has been successfully added to new_group. message is shown

The role is listed