Completely uninstall iOS App and all associated data
Please try the following:

Go to Settings --&gt; General --&gt; (iPhone/iPad/iPod/ect.)Storage --&gt; Select app and &quot;Delete App&quot;

Go to Settings --&gt; Profiles &amp; Device Management (Could also be called &quot;Profiles&quot;, if you don't use this feature, it will not be there) and delete any app data.

Go to Settings --&gt; [Your Name] (At the very top) --&gt; iCloud --&gt; Manage Storage --&gt; Select the app and &quot;Delete Data&quot;

Delete and re-install the &quot;Test Flight&quot; app

Completely reset the device (Press and hold Home and Sleep until the Apple logo appears)


5a. If this device is only for testing, you can go to Settings --&gt; General --&gt; Reset --&gt; Reset All Settings

Reinstall the app

Let me know if it works!