Ji.
I've managed to get this to work now.
note: There really needs to be better support mechanism put in place to deal with customer issues. I understand the issues with time difference and covid-19 but the current response times of 2 - 5 days between emails, is not a viable solution to deal with faults easpecially for a product that costs lots of money and has minimal instructions on how to resolve issues.
In any case, as I have a background in linux I figured out that the issue was more than likely with the Pi4 USB Stack. This was also confirmed by the following site. https://www.yoctopuce.com/EN/article/how-to-fix-raspberry-pi-4-usb-stack
Now, not sure if this is a problem with all ASIAIR PRO's shipped or if I got a "dodgy" one, but I was able to resolve the issue with the Camera freezing when connected to the ASIAIR PRO. The App 1.4.3 (5.05) also now picks up the camera in the MAIN Camera drop down list.
I am not going into FULL detail here (if anybody wants to PM me, I am more than happy to share how/what I did in more detail) on how I logged into the ASIAIR as ZWO will more than likely not approve (but I did pay for it so I should not doubt be able to ensure it works if the support channel is not helpful) and it will no doubt invalidate my warranty (i take full responsibility for MY OWN ASIAIR / PRO if it gets bricked, not anybody elses)
anyway:
1) You first need to edit the /etc/apt/sources.list and un#hash the second line in the file.. The first repository didn't work for me, but the .cn one did. so it looks like this
#deb http://raspbian.raspberrypi.org/raspbian/ buster main contrib non-free rpi
deb http://mirrors.ustc.edu.cn/raspbian/raspbian/ buster main contrib non-free $
#deb http://mirrors.ustc.edu.cn/raspbian/raspbian/ stretch main contrib non-fre$
# Uncomment line below then 'apt-get update' to enable 'apt-get source'
#deb-src http://raspbian.raspberrypi.org/raspbian/ buster main contrib non-free$
2) you then need to edit the /etc/resolv.conf and add the following nameservers to the list
nameserver 8.8.8.8
nameserver 8.8.4.4
otherwiese you will get a
Temporary failure resolving 'mirrors.ustc.edu.cn', when you try and run the next items:
Once you've done that, run the following:
sudo apt-get install rpi-eeprom
sudo rpi-eeprom-update -a
sudo reboot