Obviously I understand this is an experimental build but if it helps...
On one of my machines, the "Enable" option for Ncrunch is grayed out. I've tried reinstalling Ncrunch and have also gone through the solution removing all legacy ".ncrunchproject" files, the working folder and anything else that seemed to Ncrunch-related.
Another clue may be that when I choose "Tests" (Extensions/Ncrunch/Tests) I get a "Microsoft Visual Studio" error dialog claiming "Object reference not set to an instance of an object".
I'm using the latest build of VS2019 as well as the latest Ncrunch (mar 10).
Strangely, Ncrunch appears to work on a difference machine using the same version of VS2019 and the same solution.