The one thing I see that MIGHT be a problem is the Prolific USB to Serial Adapter. FTDI adapters are much more compatible.
Prolific adapters are known to be problematic but if it is working with one radio it should work with the other.
The cable between the 7000 and the CT-17 should be an 1/8” mono cable. I have seen with my setup where one 1/8” cable wouldn’t make a connection when plugged in. Used a different cable and it worked.
Otherwise, I haven’t a clue why it’s not working.