GearVR S8+ Vulkan - HMD initialization failed

I´m trying to get a simple VR running for GearVR. I followed all instructions and created a Blank Blueprint project as well as a 1st and 3rd person template. The outcome is always the same. The application is playable but:

a) It doesn´t come in stereo view.
b) The viewing angle doesn´t follow the movements of the phone/HMD.

Reviewing the logs I got following messages every 0.5s until I close the application:

   11-17 14:47:52.419: D/UE4(27613): [2017.11.17-14.47.52:419][ 56]LogHMD: HMD initialization failed
    11-17 14:47:52.443: D/UE4(27613): [2017.11.17-14.47.52:443][ 57]LogHMD: Initializing OVRPlugin session

I´ve tried both using the HMD and running the app in GearVRService´s developer mode. All the same.
I´ve attached a complete log.

link text

I don’t think GearVr supports Vulkan just yet

I get a black screen with anything else than Vulkan and the App crashes.
With Vulkan enabled I can see my terrain and everything, only the camera doesn’t follow the HMD movements and I get those warnings.

Were you ever able to get this to work?