Same issue here. Developing onto several devices for test demos at work. Testflight doesn't recognize that there's an update until I restart the app, and it doesn't Auto-Update despite it being enabled.
Test devices are iPads of varying model.
All devices are constantly connected to WiFi.
All devices are logged in under the same "Visitor" apple account.
Automatic downloads (Apps and App Updates) are enabled in iPad settings.
I even went as far as expiring the previous builds. On test devices, I'm still able to load the old build. TestFlight is simply waiting on me to manually prompt it to update.
Any thoughts?