OK, here's a clue. The icosahedron demo works on a machine with OS 10.15.7 (Catalina) but not on a machine with 11.2.3 (Big Sur).
Still looking ... but is it some security issue with application receiving keystrokes?
As suggested I ordered a Space Navigator ... I get the same issue as with the SpaceMouse. Controls are listed but I get no values.
The device registers as a SpaceNavigator in Vuo.
Works in other apps. The icosahedron example doesn't work.
So seems like a different issue.