I've sent several invites to a tester, and he has accepted them on his iPhone 6s, but the device ID does not appear in Fabric. Here's what appears when I view the user:
Screenshot of user profile in Fabric
As you can see the iPhone 6s appears under "devices" but the top tab still reads "0 devices" and the UUID cannot be found anywhere. Am I missing something? Is there some reason why his device might be failing to send the UUID?