Pryde it could be something to do with the cable that I am using (USB to RS232) rather than a bug as such in the ASI Air Pro.
Others are having trouble too, albeit mainly with NexStar mounts. It could be some initialization steps that the mounts need, while my simulator is up and ready to go from a home position that I can preset in the program.
[EDIT: oops, you did say you are replacing with EQMOD, and not another RS232 adapter... sorry]
Instead of getting a RS232 adapter cable, perhaps you can bite the bullet and just get an EQMOD cable, if one will fit your mount. EQMOD is basically talks directly to the motor driver interface (instead of going through the SynScan protocol).
With EQMOD, the computer (ASIAIR in this case) becomes the one that determines how to move the motors during a GOTO, for example, instead of the mount computing the motor movements. Ditto Meridian Flips. With EQMOD, the computer is the motor driver. I think ASIAIR uses the INDI EQMOD driver.
IMHO, the less you depend on the firmware in the mounts, the better off you are. You should see the protocol document for my RainbowAstro mount -- four landscape pages in clean table format. While the SynScan goes on for pages and page, with tons of footnotes to address each firmware version, with each mount model needing a different firmware version. RainbowAstro has one fixed protocol for all of their mount models (with a single menu item in ASIAIR).
SynScan and NexStar has become patches on top of patches. And it seems that instead of fixing the root cause in the firmware when a problem occurs with a specific model, they just add more special cases in the protocol to address problems from specific models, pushing the problem to INDI and ZWO, instead of fixing the problem in the mount itself.