GearVR back button disabled after returning from global menu

I'm having trouble implementing the proper back button functionality.. I'm detecting the long press similar to how it's set up in the sample SDK file, and it goes to the OVR Platform Global Menu correctly, but after it returns the back button is disabled the first time you press it.

I tried just logging

Input.GetKeyDown(KeyCode.Escape)

in Update and it doesn't log anything until I press/release the back button once. After that it works like it should again.

I also have the single press back button going out to the PlatformUIConfirmQuit screen, and if you return from that the back button works fine, it's just on return from the Global Menu it's disabled until you click it once.

thanks for any insight!
-kc