David,
On the Win10 PC, can you try this troubleshooting step from our FAQ. With only the TG attached to the PC, (disconnect the SA).
“Ensure the driver was configured correctly by your system, In the device manager, find “USB Serial Converter” in the “Universal Serial Bus Controllers” tab. Right click and select properties, select the “Advanced” tab and ensure the “Load VCP” box is unchecked.”
This might be the source of the issue.
Regards,
Andrew