App Crashing on Start up

Can you assist? We have an app that is currently in use, but on devices running iOS 9.3.5 the app flashes up and then closes. If you double click the home button, you can see the flash start up screen of the app.

What is also really strange is that the app works fine when installed for testing from an IPA file, but as soon as you install the app from the app store, that is when the issue occurs.


App Crashing on Start up
 
 
Q