I found a solution via a Windows 10 chat site; It recommended a software tool which I downloaded (it's free) & ran. Cleared all my old comm ports of devices that were not connected.
The assignment & subsequent non removal of comm ports seems to be an ongoing niggle point with Win 10 users & for good reason.
Try the program, see if it works for you. I have had no adverse effects, worked as described.
Name of the program you want is:
COM Name Arbiter Setter V0.7
- gives control over reserved COM port numbers
URL is:
https://www.uwe-sieber.de/misc_tools_e.html
Scroll down the page the program you want is a bit over halfway down the page. There are other tools on this page that may or may not be of use to you. Can't vouch for any of them as I haven't used them. Description of what each one does is on the page.
Hope this helps