OpenVR ResetSeatedZeroPose() immediately gets set back to where it was after 1 frame

Have implemented the following code (that used to work), to recentre the VR view in OpenVR() using the SteamVR plugin v1.2.1:

Valve.VR.OpenVR.System.ResetSeatedZeroPose();
Valve.VR.OpenVR.Compositor.SetTrackingSpace( Valve.VR.ETrackingUniverseOrigin.TrackingUniverseSeated );

Now it only sets the view for 1 frame before then going back to where the camera was looking previously (if I press it rapidly I can see the view being set correctly). Am using 2017.1.3f1 (later versions of Unity breaks the physics calculations) with an Oculus Rift.

Has anyone had a similar issue or knows of what can now be used to reset the view?

For anyone else having problems with recentering; by using the

[SteamVR]

prefab, the Tracking Space field can be set to Seated as an option and this allows the game to work with re-centering as a seated game. So simple but only found it after days of searching through all kinds of mis-explanations and over-complex responses.
Hope this helps someone else.

This answer may be correct, but it doesn’t mean anything to someone just starting with VR. Could someone please explain what this means and where to find it?