For those using Oculus, I would have a look at the Oculus log from within the Oculus debug tool. You need to understand if there is an attempt to start the VR mode but, for some reasons, it doesn’t work or there is no communication at all between the UE exe and the Oculus API. The debug log will show that.
On another note, I assume the Oculus plugin is installed. If you close the Oculus home, when you start your VR packaged application, the Home should open again. If it doesn’t, it means your application is not initializing the plugin and it is not being seen as a VR application at all.