So, this is what I find.
I copied a known good boot disk in 1.44mb format as blank.img to my AO486 directory. There I mounted it, and changed the boot order to HDD/FDD. I booted into Windows, and when I try to access A: in any manner, ao486 hangs with an hourglass. The hourglass will not move, the core freezes and requires a complete reboot.
So, I tried again, but I rebooted into DOS from Windows 95. When I try to access the A: drive, the same thing happens.
So, I changed the boot order to FDD/HDD and boot from the blank.img disk. That worked fine. Once there, I changed to C:\, and that worked fine. From C:\ I executed
a:\format a: <RETURN>
And formatted the A: disk. After the format was complete, I did a directory on A: and verified it was now blank and formatted by ao486.
I rebooted, as A: was not a boot disk, it booted from C: and in Windows Explorer I tried to access the A: drive again. Same thing, it hangs hard with an hourglass.
Basically, if I boot from Windows, any attempt to access any media in A: seems to hang the entire core.