Resharper - Inconclusive: test not run on debugging
I've solved an issue by installing 2020 EAP version of resharper (2020.2 EAP). Seems like it's a bug in 2020.1.4 version.
I started to have exactly the same issue after i updated VS to 16.7. Funny thing is that it broke unit test debugging in Rider as well.
Microsoft has pushed new Microsoft.NET.Test.Sdk
package, but looks like it does not help. As a workaround, you can launch test from VS Unit Test window, instead of Resharper's one.