It seems IHeadMountedDisplay::SetInterpupillaryDistance is not supported by the OptriTrack OculusVR plugin. I get this error when calling it:
11/04 10:28:47.817 {!ERROR!} [Kernel:Error] OVR Error:
Code: -1005 -- ovrError_InvalidParameter
Description: ovr_SetFloat: invalid property name "IPD".
OVRTime: 79623.655883
Time: 2018-04-11 10:28:47 [817:399:100]
(Please note, this error is seen in the Visual Studio output window, not the Unreal Editor's output log window.)
Is there some other way to set this property?