I have used this successfully in .net core web api. works like a charm.
I am currently updating some older .net framework 4.7 WCF, converting the class libraries to .net standard 2.0

Everything seems to work in Visual studio 2019.
The issue comes in with my build server and ncrunch. I discovered that I need to include Mircrosoft.Bcl.AsncInterfaces.
But it is still failing for the following error and if there is something else I need to include.

Type: Failure
Message: Dasync.Collections.ParallelForEachException: One or more errors occurred.
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
at Bci.Provider.Wcf.Dal.Updates.ProcessProvider.d__2.MoveNext() in D:\Go\A\pipelines\BCI.Provider\src\Wcf\Bci.Provider.Wcf.Dal\Updates\ProcessProvider.cs:line 50
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter1.GetResult() at ProviderSrvcTests.PutProvider_UpdateTypeServiceCallTest.<SoapCallForUpdateReturnsValidResponseTest>d__1.MoveNext() in D:\Go\A\pipelines\BCI.Provider\src\UnitTests\ProviderSrvcTests\PutProvider_UpdateTypeServiceCallTest.cs:line 40 at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Xunit.Sdk.TestInvoker1.<>c__DisplayClass48_1.<b__1>d.MoveNext() in C:\Dev\xunit\xunit\src\xunit.execution\Sdk\Frameworks\Runners\TestInvoker.cs:line 264
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Xunit.Sdk.ExecutionTimer.d__4.MoveNext() in C:\Dev\xunit\xunit\src\xunit.execution\Sdk\Frameworks\ExecutionTimer.cs:line 48
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Xunit.Sdk.ExceptionAggregator.d__9.MoveNext() in C:\Dev\xunit\xunit\src\xunit.core\Sdk\ExceptionAggregator.cs:line 90
at System.Threading.Tasks.ValueTask.get_IsCompleted()
at Dasync.Collections.ParallelForEachExtensions.<>c__DisplayClass1_0`1.<b__0>d.MoveNext()