On my laptop that I use for observing, all inversion modes work normally.

But on my desktop, if I am in the Uninverted mode and switch to Mirror
E/W, nothing happens. Switch to Mirror N/S works fine.

In the Inverted mode, just the opposite: Mirror E/W works but Mirror
N/S does not.

The same happens in all Up modes.

Strange.

Chuck Baker
Carlsbad, CA