Is it a track-ball, a rotary encoder, and a 3D stick?
It's flexible, and there are LEDs and linear optical sensors set up with an occluder in between that casts a shadow (or passes a light through a slit, according to the patent). The sensor detect where along the sensor the shadow or light falls, which indicates how much you have translated or rotated the control in a particular axis.
1: https://www.fictiv.com/teardowns/spacenavigator-3d-mouse-tea...
Mechanically, it’s something like an Rx/Rz two-axis joystick with sliding knob part on top that can be slid in X/Y, pushed/pulled in Z and twisted in Ry as well. All axes are spring centered.
It have the same issue for my Logitech G600 that it can't pick up some inputs. I set up the macros in LGHUB with keystrokes (multiple modifiers with keys) and use AHK to grab those and expands the capabilities of my G600 than what LGHUB offers.
I found it interesting how companies invest heavy in hardware and don't bother to improve the software side.
If anything the hardware is the hard part to copy and open source drivers could do nothing but benefit them and ensure wide platform compatibility and longevity, and yet so many companies like this insist on closing things up and forcing hackers to reverse engineer everything. It's bizarre logic to me.