anybody having problems tex mapping coor from another object?

It works in a small test case but for some reason my main project is broken.
My particular project is using a very large landscape mesh (1K x 1K) with one large projected ground texture.
I separated the mesh into two objects so that I can modify the materials, but they both need to share the same image.
I’m not using UV mapping because of memory limits.

(tried it with my working copy as well as the lastest build)

If needed I will try to upload the blend file, but because of the large sizes it will take some effort.

trying to find out if this is a bug, thanks