Aloha,
I have purchased the Rockstar and we are also having an issue with the menu on mobile (iphone 6S v. 12.3.1 physical device) also all emulated mobile devices as well.
My site I have the following menu structure:
Main -> sub -> sub -> sub -> sub -> sub -> sub -> sub -> sub -> sub -> sub
Main
Main -> sub
Main
On desktop this all works golden… On larger mobile screens is okay with this number of top level and sub level menu items
On the smaller screens the menu opens, but does not scroll. The main page scrolls, but cannot see lower sub items at all.