In tvOS 14.+ I experienced a similarly undesired behavior. When I launched the TopShelf extension in the tvOS Simulator, using TopShelf as the Run Target, everything went fine all the time.
When TestFlight users installed the app with the newly included TopShelf extension, the TopShelf did not load. Only after a power cycle, the TopShelf Items showed up.
How is that feature supposed to work for apps which provide a TopShelf extension only as a later addition? Will the users honestly have to pull the power plug before they can see it?