Not launching debugger

Hi all-

I'm having an issue wherein when I try to debug a test, it just sits there with the waiting animation next to the test name. The debugger doesn't launch. Here's the output in the "Test Explorer" output window:
```
Test run for Esi.Core.Tests.ToyUnitTest.ReadSchemaTest, expecting 1 test results file(s) in total
Executing dotnet build in c:/code/esi/src/core
Executing dotnet test --no-build --logger "trx;LogFileName=C:\Users\jodemme\AppData\Local\Temp\test-explorer-g26BGW\0.trx" --filter "FullyQualifiedName=Esi.Core.Tests.ToyUnitTest.ReadSchemaTest" in c:/code/esi/src/core
Process 32220 started
Waiting for debugger to attach
Waiting for debugger to attach
Waiting for debugger to attach
Waiting for debugger to attach
Waiting for debugger to attach
Waiting for debugger to attach
Waiting for debugger to attach
Waiting for debugger to attach
```

This is an nunit test which runs fine with 'dotnet test' at the console. It is in an sln which is not at the root directory. It is targetting dotnetcore3.1 and the csproj has the following references:
```



```

I'm running VSCode version:
```
Version: 1.42.1 (system setup)
Commit: c47d83b293181d9be64f27ff093689e8e7aed054
Date: 2020-02-11T14:45:59.656Z
Electron: 6.1.6
Chrome: 76.0.3809.146
Node.js: 12.4.0
V8: 7.6.303.31-electron.0
OS: Windows_NT x64 10.0.19041
```

I think this worked on a difference C# project... Am I doing something wrong? Or is this a bug?