When porting code from a previous .NET 4.7.1 application I encountered the following problem:
When the unit tests projects are .NET Standard/Core projects the unit tests are detected but not executed.
There is already a support ticket for this issue that seems to be resolved. Maybe it will be included in the next version.
As a workaround I changed the test projects to .NET 4.7.1 as target framework.
Afterwards the tests are executed again unless they are inherited from a base class that is located in another assembly.
When placing the base class in the same assembly everything works fine.
This functionality worked fine in the past (even across assemblies) if all projects are referencing .NET 4.7.1 as target framework.
I attached a Demo project and screenshots of a loca test run (Run all)