Timewarp broken in 1.35.0 ?

Hi,
I currently have two games published on Steam since some months, recently people updated to 1.35 and complained "everything does not work any more", the camera/tracking becomes all jittery/erratic and looks like "watching through a wobbly pudding".

After re-compiling everything, upgrading the firmware/etc. I see exactly the same they see.

I manage to track down the problem and seems this happens when I enable, in my code, the Timewarp feature.

Now the difference with/without it, is minimal, visually "none", in code, little.

My code more or less does "about the same" that is doing in OculusRoomTiny with the differences :

1. I use the "waitframe" method
2. I use FSAA ( so I have some more texture to resolve in )

The almost only differences between timewarp/non timewarp are that when I call :

p = ovrMatrix4f_Projection(eyeRenderDesc[eyeIndex].Fov, zNear, zFar, ovrProjection_None);

there's also an

#ifdef DO_TIMEWARP
posTimewarpProjectionDesc = ovrTimewarpProjectionDesc_FromProjection(p, ovrProjection_None);

proj = Matrix4(p);
#endif

and a bit later on :

#ifndef DO_TIMEWARP
ovrLayerEyeFov ld = {};
ld.Header.Type = ovrLayerType_EyeFov;
ld.Header.Flags = 0;
#else
ovrLayerEyeFovDepth ld = {};
ld.Header.Type = ovrLayerType_EyeFovDepth;
ld.Header.Flags = 0;
ld.ProjectionDesc = posTimewarpProjectionDesc;
ld.SensorSampleTime = sensorSampleTime;

#endif

For the rest "the main cycle is the same", it was all working before this latest update now it doesn't.

Any suggestions what I should look at ?

Thanks in advance.