ADB debugging on Android 4.2.2
If your recently-updated Nexus 7 (or other Android 4.2.2 device) no longer allows ADB logging and so you can't test your game, try the following drivers:
Open Control Panel > Device Manager and update your Nexus to use those, then check "adb devices" in order to confirm the Nexus can be seen again - be aware you may need to do "adb kill-server" first.
You will get a prompt at this point, ensure you allow the Nexus to talk to the PC (probably best to set the tickbox to always allow this PC...). Now try building inside GM again. It should all be working fine again now. If these drivers failed to fix, check your device manufacturer's website for alternatives.