Strange display errors inside the camera rig (both eye anchor)

Hi everyone,

I'm developing a simple vr application in Unity 3D for Oculus Rift. I'm Using Unity Oculus Utilities 1.26 and Oculus Avatar SDK 1.26. I've noticed these strange errors inside the both eye anchor (Camera RIG, oculus default prefab): there are some many grey elements flickering and disappering on the screen. On the cameras is aplied Post Processing Stack (I've tried disabling this, but I've the same problem). Do you know what is the cause of this error?  I've choose the wrong rendering mode? The UI can give these strange problems?

I've attached some errors screenshot and rendering settings.  



Thanks a lot!