Hello,
I am trying to disable the mouse rotation for my vr game, but I need the control rotation to keep working for the headset. I want my player to be able to look around with the headset but not with the mouse. Is this possible?
Thanks.
would really be interesting to know. Played around with IgnoreLookInput but this disables control rotation alltogether…
Go to your Project Settings → Engine Input → Turn Function and then remove the Mouse Axis from your turn methods. I hope this works. I don’t want to plug in my Occulus Rift to figure this out! 
Had the same problem. In my case that helped:
Always make sure to have a VR Gamemode, that is set as the default Gamemode in the World Settings.
If you don’t do this, UE4 seems to use some Default setup that uses the mouse as input.
For UE4.15 go to Project Settings > Engine Input > Bindings > Axis Config > MouseX , MouseY. Set all parameters to 0.
Controlplayer → set ignore look input → true
Reset ignore look input