When I go to the Test Cases tab, the Run Test(s) tab swirls once and stays grayed out (see below). I am not able to run the test cases. When I select one test case, the Run Test button stays grayed out. Neither situation produces a visible error message. 

On the contrary, when I go to the Test Cases tab for the QDM version of the same measure, the Run Test(s) tab is active after swirling for a minute or so, and I am able to run the tests.