The current integration of tree snapping with MoveIt mod is not perfect, and there are things I wish were done better, but can't realize due to how MoveIt handles its tree positions relative to the mouse position.
In order to bring a better experience, the internal framework of MoveIt has to be adjusted, but this is a large project and will take time.
For now, please give me some input in how you'd like tree snapping to function, and I'll try my best to realize it.