We just upgraded from 2012.2.1420.0 to 2015.2.715.0. Everything was working fine under the older version - but we are seeing the following issues under the new version: a) No tests being listed in Test Explorer. NOTE: This happens EVEN if the test project is NOT a Test Studio project and even after a Rebuild All. b) Group By dropdown is empty. c) Installation of the new Test Studio seems to have played havoc with my Visual Studio environment (previously displayed windows/panes no longer visible, etc.). Visual Studio Version: 2012 Update 4 Test Studio Version: 2015.2.715.0 NOTE: #1 is a critical (show-stopper) issue for us as we also support Specflow test projects for which the Test Explorer is the ONLY way to run these tests on local. My coworker reported that the Group By dropdown contents were restored when she installed the NUnit Test Adapter - but went away the next time she reopened Test Studio. The tests still did not show up in the Test Explorer - even for non-Test Studio projects.