The rights buttons for Unregistered Users do not display anymore the value set after page refresh

Steps to reproduce

1. Go to Administer Wiki > Users & Rights > Rights (or Extension Rights), this can be reproduced also on Page Administration
2. Click on 'Users' radio button
3. Set a right for Unregistered Users, e.g. click on 'Comment' right button
4. After the green check mark appears (or the red X mark, depending on the right that is being set), refresh the page (F5)

Expected results

The green/red check mark is still visible on the rights button, e.g. under 'Comment'.

Actual results

The right button does not display visually any value.

If the mouse is hovered over the rights button, the tooltip displays the value that is really set.

The issue could not be reproduced on earlier XWiki versions.