I didn't find any mention here or in the manual of VC shadow glitches or disappearing VC shadows in the main window if new view windows are created but that is what I'm getting.

If I undock it and put the new view onto my 2nd monitor, the main screen VC shadows correct themselves once I change to a new Ezdok VC position.

I'm guess this is just a matter of nothing is perfect nature of the beast?

I need to ask in case there is a setting that could alleviate this as I often fly with a 2nd viewport in the corner of the main 4k screen.

I am not aware of any specific issue, it may be ezdok related - can you test without ezdok?

I have disable Ezdok in the exe.xml with 'true' and the same occurs using the default FSX camera/view systems.

I will have a look, it looks to me from your picture as if some of the fixer corrections aren’t applied. The shadow on the seat is basically correct but of poorer quality, the shadow on the back wall has the wrong offset away from the sun  that the default fsx applies. I don’t know whether it can be fixed.