Timbo I bought a brand new CGX Celestron mount as well.
1) First confirm that your mount has the Prolific chipset. See post #51 of this thread:
https://bbs.astronomy-imaging-camera.com/d/12787-connecting-asiair-pro-to-celestron-evolution-mount/50
2) if it does, then the problem is simply the lack of the Prolific USB virtual serial port driver (the USB chipset inside the mount).
3) you can wait for ZWO to do a real ASIAIR app update that was promised for sometime this month. That update, as promised, will contain the Prolific driver, and when you update the firmware, your ASIAIR will be able to see the mount.
If you prefer not to wait, and you have a version 2 ASIAIR (the Raspberry Pi 4 based ASIAIR; ZWO calls it a "PRO"), you can fix it now by burning a new firmware image which ZWO had released as a temporary workaround to fix an "EQ6-R Mount problem." It is the same problem -- newer EQ6-R uses the Prolific chipset. To do that, download and burn the image that is mentioned in this link:
https://bbs.astronomy-imaging-camera.com/d/12655-how-to-connect-the-new-sky-watcher-eq6-r-pro-to-asiair
Not mentioned by ZWO is that this image will only work with version 2 of ASIAIR. It will not work with the original ASIAIR (the one that came in the Raspberry Pi red and white plastic box). Further, as the folks in the first link has found out, the "EQ6-R" image is also larger than 32 GB, and you will need a larger microSD card to burn that image into. 64 GB appears to work dandy for the people who participated in that thread (I recommend reading that thread carefully starting at post #51 -- the first success was reported in port #64, followed rapidly by the other two that were affected -- all three of them have working drivers today).
If you are using Apple Pi Baker to burn Raspberry Pi microSD cards, in addition to using a 64 GB microSD card, it was also advisable to first uncompress the RAR file (the one from the Google drive in the "EQ6-R" link from ZWO). After uncompression, you will have an IMG file (Disk Image). Point Apple Pi Baker to the IMG file. Apple Pi Baker does not reliably uncompress an RAR image on the fly. (The RAR is about 11 GB, and the IMG is about 32GB.) This was also discussed in post #76 and #77 in that same "51" thread.
As mention further down the "51" thread, be damn sure to use a microSD card that is larger than 32GB.
Chen