Please try the same by using a "3d Vector from 3 Coordinates" instead of "3d Vector" for the second node, the one that creates the vector with Z=0. It seems to be working completely for me. As for the instance node, it has problems indeed, we'll investigate them.
Ivan Kolev (Software Developer, EPHERE Inc.)
E-mail: ivan.kolev at ephere dot com
Discord: ikolev