I've narrowed down what is going on, but I'm pretty surprised by it and it has nothing to do with the firmware upgrade (just a coincidence).
To work with my Coco3 I use an external power source since I cannot get the voltage/power necessary from it. That works fine.
On my ST I was using the same power source and it wouldn't work at all. I plugged the ST floppy power into the HxC and it worked fine.
Why would this happen?
Answers : The ST +5V voltage and the external PSU voltage is too much different.
Check both voltage with a voltmeter.
Ok, I can do that. I guess I don't understand how it would make a difference. The external power supply is powering up the HxC. This works fine w/ the Coco which is in essence doing the same thing.
Unless, the 5V from the power supply is somehow used in the communications over the floppy connector and for some reason those need to match up with what's actually IN the ST.
I'm no electronics expert so this is very interesting to me.