Hello. I found the answer to this question. The system works without fail regardless of (Anchors) or (Screen Size). Hope I could help you !!!
Thanks a lot, GetViewportScale - partially solved my problem but adding the Absolute to Local node - solves everything perfectly, why it is so magical - i am trying to investigate now )
This appears to be fixed as of UE5.0 Preview (I no longer need to divide the GetMousePosition node output by the viewport scale to get the correct location on my machine, in my test project)