Going to the Oculus home screen is the new default behavior and can be disabled using the the CVar "gearvr.HandleBackButton". Once this new default behavior is disabled the button bindings should work as expected.
This is regression from 4.10 functionality. When assigning the Android Back Button functionality in a GearVR project, the back button will now bring up the Oculus Home Screen asking if you would like to exit.
Working: 4.10.4 - CL-2875303
Tried testing in Dev-Mobile CL-2896993 and Dev-Main CL-2897022 but was not able to get a successful build. This may affect other versions than the 4.11 release.
1. Open UE4
2. Setup the project for use with GearVR
3. Assign the Android Back Button event some functionality
4. Package the project or launch on the device from the editor.
5. When the project is loaded hit the Android Back Button
*Note: This works in developer mode, where the GearVR headset is not needed, and with the GearVR device
Results: The oculus home screen will come up asking if you want to exit the game
Expected: the assigned Android Back Button event will perform assigned functionality.
Head over to the existing Questions & Answers thread and let us know what's up.