I just went on a hunt for my template after noticing it had been missing since the 2017.09 update.
Discovered that my Cakewalk preferences had been overwritten for the default folder locations. Why did that happen?
All my custom path settings were wiped out and replaced with 'C:\Users\
username\AppData\Roaming\Cakewalk\SONAR Platinum'.
After pointing the 'Templates' path back to my original location, the default template is working again. Although I had to reset my 'Default' template to the correct one, because I had changed it in my attempts at fiddling around.