The orange dot next to app name sometimes does not show for beta version app

We download our app from TestFlight, it shows the orange dot next to the app name as expected on some devices. (Since this is a beta version, there should be the orange dot according to the TestFlight document.)

However, in other test devices, the orange dot does not show or show at first and disappears after swiping, even the apps in TestFlight are in exactly the same version. Is this a bug or expected behavior?

The orange dot next to app name sometimes does not show for beta version app
 
 
Q