Your FreeCAD info shows a fancy version number, ist this an official 0.18 version or did you compile yourself?
It's one I built. The latest version available for fbsd is 0.17 and none of them are "official" builds.
Regarding move, the behavior I see is as follows:
If I have the axonometric view set, when I press on the middle of the navigation cube, it does not move until the pointer leaves the cube. So it appears to not be moveable unless you move the mouse a significant distance. There is an obvious circle in the middle of the cube, which is used to set one of several axonometric views depending on the current orientation of the object. If you are already looking at that axonometric view, the area appears to be non-functional. Similarly, if a single face is showing, the face appears to have no function, and I still need to drag to the edge of the cube to get it to move. This should not be necessary.
A clear distinction can usually be made in terms of intent when a user presses and drags, vs. clicks (presses and releases) a mouse button (Modulo some small delta to allow for shaky hands). That distinction is apparently not being used for navigation with the nav cube.
To be clear on the registration issue: If you place the pointer where it is in the image below, do you see a blue or a white background in the curved arrow under the pointer, and if you click does the 3D image rotate? In my case, the background is white, not blue, and the image does not rotate. Note that the pointer is well within the underlying arrow image; if it is moved lower the background will turn blue and it functions correctly. I can also get the various parts to highlight blue and function by moving the pointer near them (generally below), but not actually inside them.
Edit: we need to create a wiki page for it...
I was going to do that, but wanted to understand how it's supposed to work first.