If you are broadcasting from a v1076 AppGameKit IDE to a v1074 Player, that might be the entire problem.
It's not impossible that v1074 has issues with transparency in the Mac Player (which I just discovered is available in the Mac App Store).
Have you tried running on any other device (Player)?
Since you have a Mac, you should be able to create the Mac version of your app and see if it runs properly that way.
I would recommend upgrading to v1076, which is quite stable. But you would then have to build the Mac version for testing, since there isn't a v1076 Mac Player.
And, you will need to build on your Mac for final production for the Mac world anyway.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master