WRTP528

I own several KG-1000Gs and love them. But I’ve never used a cable to program it. (Although I have for other radios.) Out was pretty easy to do it manually so I never bothered doing it the other way  
If it doesn’t work through the programming software, try importing the information through the face or mic. It is pretty easy to do and might give you an alternative to set the repeater information correctly. 
Just a thought in case you can’t get the connection to your computer program to work. 

Steve, thank you for your explanation. Mark, thanks very much for the link -- I will check that out.
KAF6045 in Lowell -- I used in to live in GR. ? Thanks for the advice on configuring the port (good old Device Mangler) and advice for testing.
Such a friendly forum! Thanks, all!

I have a few radios using similar programming software, and the port selection dialog comes up greyed out for them. I had to use the Windows Device Manager to locate the COM device in question, and then manually change the Windows assigned port # to match the one the programming software defaulted to. As a result, I have something like two or three different adapter cables for the radios all assigned to COM 1 -- meaning only one cable at a time can be connected to the computer.
Tones do nothing to prevent transmission... But mismatched tones can prevent /reception/! Tones are used to open the squelch on the receiving device.
However, if the transmitter is set for repeater, the receiver will not hear it -- they are on frequencies 5MHz apart. Both devices need to be set for simplex -- try channels 1-7 in the unified channel listing as they are simplex only with a 5W ERP limit (you may also want to ensure both radios are set to the same bandwidth; wide FM, not NFM).

The Windows driver for the USB programming cable/cables is probably not loaded or incorrect. 
See https://www.buytwowayradios.com/blog/2021/06/how-to-install-the-wouxun-programming-cable-and-driver.html
 

I suspect the KG1000 is transmitting just fine but either the 905g is being swamped by the power (de-sensing) or that the 905G is listening on a different frequency and/or using a different tone. 
I suggest you clear out all receive tones first and make sure xmit and receive are all on the same frequency.