playing audio files from resources is troublesome with Qt 5 at the moment and we have reported this as a critical bug to Digia which will hopefully be fixed with the next Qt release.
At the moment, you can do the following to work around this bug:
1. Do not use the BackgroundMusic element, but instead the SoundEffectVPlay component and convert your music to a wav file. That way you can keep the qrc deployment.
2. Switch to non-qrc deployment (but with assets folders). See the Squaby demo .pro file where this is done because of the same reasons.
Please watch the changelog of the next V-Play updates to get notified when this bug is fixed by Digia and incorporated to V-Play.