I installed Build 804 and was initially able to run unit tests normally. For no apparent reason, running unit tests from R# stopped working. I created a new project with 1 class that has 1 simple unit test. I tried running and debugging using the side button in the source code, the Solution Explorer, and the Unit Test Explorer windows. This creates new unit test sessions, but these sessions never terminate, nor do the debugging sessions ever hit the first line of my code. I tried installing build 809, but still encounter the same issue.
Unit tests run fine from the NUnit GUI.