I have a published Xamarin.iOS app (https://tiny.cc/strumios) which no longer runs in the background. This began yesterday, and I have no idea why. It only happens on my iPhone 6, but does not happen on an iPad. Both devices are on iOS 9.3.1. It had been working fine before this.
The app plays streaming audio, and when placed in the background the app stops after 90 seconds. When I run it again, I see the app's launch screen. This leads me to believe the app is being terminated, not merely suspended.
Other audio apps continue to play in the background on this phone. Also, I have a similar Xamarin.Forms app which also plays audio in the background just fine. The Xamarin.Forms app uses the same audio code as the Xamarin.iOS app. Of course, my Info.plist is set correctly as it has been working fine until yesterday.
Restarting the iPhone and reinstalling the app did not help.
What could be going on?