Odd flickering in viewport 4.19

I am getting a strange flicker in view port since updating to 4.9

Also note I can no longer see my foliage not sure if thats due to it having a material on it so its always facing the camera.

In game when launched it looks fine though.

Fixed issue by deleting my foliage which uses a screen offset to always face camera, and re-added it.

Spoke to soon, it returned when reloading the map. I have a feeling its the offset when level is loaded again into editor, this is the material on my crowd which is just planes spilled as foliage to fill the stands

Both of these cause the problems, when removing the per instance node from the material things seem to work again, of course missing out on the per instance color variance, and the wind variance, but for now is a workaround.