Render target materials display as black on mobile VR when Mobile Multi-View is enabled.
Also confirmed with LDR capture source.
User also reports issues with scene depth (potentially fixed with [Link Removed])
Confirmed in 4.23 MAIN at CL 6829265
Result: Render target material is Black on VR mobile. (Material works as expected when Mobile Multi-View is off)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-75839 in the post.