UnityIAP hangs on iPhone 6+

Hi everyone,

We implemented the new UnityIAP features and have problems running it on our devices. While it runs fine on an iPhone 5, the game alway hangs on a 6+ when trying to initialize UnityIAP. It only happens AFTER I successfully purchased a non-consumable in the sandbox environment. After a relaunch it will hang.
That's the last thing I see in the console:

UnityIAP:RequestProducts:{(
"key1",
"key2"
)}

Uncommenting UnityPurchasing.Initialize(this,builder); will make it run again,...

UnityIAP hangs on iPhone 6+