qobject_cast fails on armhf

We are trying to set up a system on an odroid c1, we've been having weird crashes. I've narrowed it down to this simple test (attached) where qobject_cast returns null for QApplication. This is obviously a big problem.

Will produce the following output:
QObject(0x0)
QApplication(0xbebcd088)

Changing the QApplication in main.cpp to the App class which derives from QApplication makes the casting work, however, the app then starts crashing.

Note that all of this works as expect on x86_64 systems.