OK, I finally bit the bullet and implemented the newer C3 SDK support for z Elevation, so it should work the same in the editor as runtime. This will require updates to the new Common "Z elevation" property. Details are in the dev log: https://kindeyegames.itch.io/c3-3dobject-alpha/devlog/560185/change-to-zelevatio...
Thanks a lot ! Sadly there's still a small bug. Now the item renders at twice the Z elevation set. For example I made a small gif. I created two 3D Objects cube, that have a scale of 16. So, If I set a Z Elevation of 16 to one of the cubes, it should render at the height of the first cube. Yet it seems to render at twice that Z Elevation. The 3DObject blue selection square is located at the right position tho. I tried with different scales, but even with a scale of 1, the issue is still there, so it's not scale related. I don't know exactly where the problem is, but there's a x2 somewhere :p.
Good to notice it's only editor related, in game it renders at the correct Z Elevation.
We're almost there !
Don't be too sad :) We got this! Thanks for the great bug report and gif. It is always so helpful to get detailed reports like this. I am a one person operation for this particular project, so I really rely on good community feedback.
A new version is going up now. Please let me know if it fixes this issue for you.