I am having the same issue, just received radio this week 8/24/2021.
I just purchased a QYT KT-8900D from amazon, and using current Windows 10 and the OEM programming cable.
This behavior is consistent between 2 different computers.
When I attempt to Download from Radio, setting to the COM port showing a prolific chipset in Device Manager, and setting QYT and KT-8900D in the model selection, and then powering up the unit when indicated by the dialog, after a very short window saying "Identifying the radio...", my radio powers off and a dialog pops up saying "Radio identification failed"
I used the test driver that Jim posted and the radio still failed to identify.
I also attempted to use the other suggested programs for this radio without success.
This is my 2nd QYT KT-8900D and I didn't have this issue with my other one, purchased this one for the car.
Any assistance would be appreciated.