Apologies if this has already been mentioned - but in my 3.1.0 sites - while creating a new TV, the list of Templates under the Template Access tab is always blank.
Yes, there seems to be a problem with the AJAX-request.
When I test it, it’s enough to just open the “Template Access” tab once again to see the list (or to select a value in the dropdown “Filter by Category…”).
Looking at the generated AJAX-request for the grid (request parameter “action” = Element/TemplateVar/Template/GetList), the problem seems to be the request parameter “category” that has a value of undefined. The request works correctly if the value is just empty.