Blank screen on Android 7.1

We tested our application on a Nexus 5X with recent Android 7.1.1 Preview and we get a blank screen only. Other android version works for us.

We tried the Qt Android Extras example but it will be shown on Android 7.1. So we replaced our own main.qml with the main.qml of that example but got no luck. It was still empty.

Here is a screenshot of the empty screen and a logcat of adb with debugging enabled.
We added a simple MouseArea over the full screen. Is it possible to "click" on that empty screen and the mouse handler will be triggered. See "HELLO!! MOUSEAREA CLICKED" in log file.

Any hints that we could try?