Using iPhone as HMD

Hello! I want to use iPhone with UnRemote 2 as VR-glasses. I have UE 4.27 installed with Simple HMD plugin activated. When I try to connect via UnRemote, something goes wrong with axis mapping. I’ve recorded a video with this issue, so check it out: UE4 VR with iPhone test - YouTube

Also, I’ve noticed that something strange was happening with calibration: when the phone is in initial position, horizon and azimuth angles are different if we compare it with start position.

In addition, when I tried to control virtual camera through UnRemote or LiveLink app, everything was good and I could easily control virtual camera orientation without any calibration or axis mapping issues.

Any ideas how to make this possible?