Yes, the tick box is tickable on Mac but not on PC. Since it doesn't seem to do anything it might as well be grayed out. Maybe it's a combination. Click it three times while in Monochrome, twice while in Hidden Line, Switch to X-ray, Switch back to Hidden Line, tick the box again... I doubt it though. I think it is either a bug or a shortcoming of OpenGL.

So 'never-paste-in-place' if you might want to reload SKPs later IS the lesson hard learnt... I had erroneously assumed that you were using import [or modeling a component in the site-plan with a 'svae_as'], so that the origin stayed true between the files...

ah, perfect!

Anssi... you are the GOD of non-coplanar fixes. Thank you my friend!