FPS jumps between 45 and 90 discretely. Oculus

Hello everyone!
I`m using Oculus CV1 now and now I need some help:( Fps in my game in UE4 when i use VR preview - jumps from 90 to 45 and back discretely.
Like something lock fps :frowning: who faced something like this?

It seems the oculus Vsync start working after patch. sorry