VR oculus rendering Issue

stragne  disortions of image affected by    movement or blinking light, even a base OVR oculus  scenes have this issus in Unity  2017.3.0f3 (64-bit). has  anyone experianced that bug?

disortions ( objects are loosings its  shapes) Objects looks like behind disorting glass,  this  affects only parts of  images, It looks like  its affected  either  by fast motion, or  fast changeds in light intensity