SOLVED.
The following errors:
Error: Assertion failed: Views.Num() > 0 && Views.Num() >= EyeIndex [File:D:/Build/++UE4/Sync/Engine/Source/Runtime/Engine/Private/SceneView.cpp] [Line: 2638]
Warning: 45 x 50 variable resolution swapchain is not a divider of 1440 x 1584 color swapchain, potential edge problems
Resizing VR buffer to 1440 by 1584
Are caused by turning CMS (cast modulated shadows) on in your directional light.
Modulated shadows are not support on Quest while using VULKAN unless Mobile MultiView is turned OFF. Which would kill perfomance so not even worth.
Didn’t even think modulated shadows were the cause because when I turned it on way back and I thought I was turning on CSM (Cascading Shadow Maps).