Blank screen after OBB downloader completes

The app loads correctly, I see the OBB downloader run and complete, but when the game moves to the next scene all I see is a blank screen with a purple colour (our background colour) and none of our actual assets. The game music is playing so clearly the OBB file is working and there's no errors in the ADB LOGCAT output that I'm running so I have no idea what's going on.

We're using a self signed (jarsigner) APK as our beta on Google Play publishing with Unity 5.6

Only happens on device, not in editor.