1. Change the theme to FluentDark using the dropdown located at the very top left of the app form (it should say Fluent as default). 
2. Select the Administration View ribbon group, located at the very left of the form ribbon
3. Select any option from the dropdown menu that appears 
You should see that the borders around the ribbon groups appear, and  once the mouse hovers over a collection is 'refreshes' them and the issue is then not repeatable for that group of buttons (even after another theme change). As mentioned in the previous ticket, this issue is only repeatable once per application launch