Hi,
For me the issue was the layout being used.
My templates were using “_Layout.cshtml” which was not created inside the Umbraco backoffice (and thus didn’t appear under the templates category). I noticed that when I created a blank template without a layout it would import correctly but with the _layout applied it failed.
If this is the same for you; create a new template for your layout in the Umbraco backoffice, enter the code, and save. Then update the layouts for the other templates inside the Umbraco backoffice. Once complete your templates should nest under the layout you created and import correctly with usync:
Hope this helps!