Steps to reproduce:

1. Go to PlatformUI, to "Admin panel -> Roles";

2. Click on "Create a role", and name it "Test";

3. Click on its name on the listing of roles, afterwards;

4. Change from tab "Test" to tab "Users and groups using the <Test> role (1)" tab;

5. Click on "Assign to users/groups" button.
The UDW should show up.

6. Choose any user / group at will and click "Confirm selection";
Back on the same tab "Users and groups using the <Test> role (1)", the view showing the new User/group should be refreshed to show it but it does not. Manual reload of platformUI is required for it to show.