We experience the exact same issue, but in our project there isn’t even “flickering”. Changing the FOV simply turns off all lights completely. That means if you try to zoom with our sniper rifle, it suddenly gets dark in the level. We are on 4.8.3.
I can also confirm that the issue is depended on either the number of objects in the level or at least the amount and/or detail of all meshes (or their distance fields) in the world. If we remove some higher poly objects the issue doesn’t occur any more.
Is there anything we can do to further help in finding the cause of the issue?
[Edit] I opened up the Kite Demo to check if I can reproduce the issue there. Turns out all you need to do is set the FOV to random values (or lerp between two values with a sin function or so) in Tick to turn off all lights and shadows. Should (hopefully) be reproducible on any machine.