Unit tests randomly discovered or else forgotten VS2015 / R# Ultimate

I have an up to date subscription to R# ultimate and a solution with 3 MStest projects in it for unit, integration and end-to-end-testing.  Thanks to a drag in VS one day, I hit the delete key while the unit test explorer window had focus and 2 out of 3 test projects had disappeared on the next test run,

I closed VS, I updated R#, I searched till my eyes bled for a "refresh tests" options and scoured the internet for clues.  I came up with zip.  

I can clean the solution, force open a UTE and run and the tests appear briefly before disappearing again.  

The only way I can get UTE to show all my tests in the session is by Run All Tests at Solution level, which is pretty inconvenient when I just wanna debug one test out of 100s.