astroMartin I, too, have a brand new CGEM II that simply will not connect to the ASIAIR Pro
Can you check if the USB port of the mount is back powering the USB of the ASIAIR? Since your mount is being powered by its own 12V source, it is possible that the power pin of the USB connector at the mount actually carries power that is higher than the voltage of the USB connector in the ASIAIR, and causing backpowering.
If you suspect that backpowering is a problem, you can slice open a USB cable (easier to do with un-shielded USB cables) and snipping the power line (usually red), and then taping everything back carefully making sure the red wire does not short to anything else.
Check "back-powering" in this Raspberry Pi documentation:
https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#back-powering
The "upstream device" in your case is the ASIAIR (Raspberry Pi).
FWIW, I have found that most power hubs cause ASIAIR to be erratic (some causing the ASIAIR to not even boot). I have so far only found a single Anker power hub model that don't backpower the ASIAIR.
Chen