Probably the one that works is the one that is in the same plane as the initial point.

The Move command uses a kind of "virtual construction plane" when working in the ortho views - that means for the second pick an ortho view's construction plane is essentially moved to go through the first pick point.

That's so for example you can pick the base point anywhere in the 3D view (at any elevation), and then switch to the Top view and then when you move your mouse around, the second point does not "slam down" on to the real construction plane (which then would produce movement in elevation which may not even really be apparent when looking in the ortho view) but instead stays in a plane going through the base point.

The Move command sets some flags to get semi-planar behavior like that, and then that is probably triggering the "on" snap suppression as describe in that previous thread. That may need a small adjustment to avoid this.

- Michael