I just tested a manual edit to:
Use a good code editor like Notepad++ or MS Visual Studio Code.
Scroll down to the
"File Locations" object and edit the entry for
Use escaped (ie, double) backslashes between directory names.
I was sucessful changing it to
Took a few times starting and restarting SU2020 to get the “My Templates” tab to appear, but it did and an old example template I had in that folder (from a few versions ago) began to appear, and I could select it as my default template.