OneWay functions with ReliableSessions doesn't work

[mconnew]

@mconnew I pulled latest master and built the service model packages but can't get a reliable session one way call to work under netcore3.1. Getting this assertion:

Process terminated. Assertion failed.
Type 'System.ServiceModel.Channels.ReliableOutputSessionChannelOverDuplex' is required to override OnOpenAsync
   at System.ServiceModel.Channels.CommunicationObject.OnOpenAsyncInternal(TimeSpan timeout) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\CommunicationObject.cs:line 561
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)
   at System.ServiceModel.Channels.CommunicationObject.OnOpenAsyncInternal(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.System.ServiceModel.IAsyncCommunicationObject.OpenAsync(TimeSpan timeout) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\CommunicationObject.cs:line 532
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)
   at System.ServiceModel.Channels.CommunicationObject.System.ServiceModel.IAsyncCommunicationObject.OpenAsync(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.OpenAsyncInternal(TimeSpan timeout) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\CommunicationObject.cs:line 504
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)
   at System.ServiceModel.Channels.CommunicationObject.OpenAsyncInternal(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\System\ServiceModel\Channels\CommunicationObject.cs:line 498
   at System.Runtime.TaskHelpers.CallActionAsync[TArg](Action`1 action, TArg argument) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\Internals\System\Runtime\TaskHelpers.cs:line 377
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.<>c.<System.Runtime.CompilerServices.IStateMachineBoxAwareAwaiter.AwaitUnsafeOnCompleted>b__5_0(Object s)
   at System.Runtime.ServiceModelSynchronizationContext.<>c__DisplayClass1_0.<Post>b__0(Object s) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\Internals\System\Runtime\ServiceModelSynchronizationContext.cs:line 15
   at System.Runtime.IOThreadScheduler.ScheduledOverlapped.Callback() in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\Internals\System\Runtime\IOThreadScheduler.cs:line 461
   at System.Runtime.IOThreadScheduler.ScheduledOverlapped.IOCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\Internals\System\Runtime\IOThreadScheduler.cs:line 434
   at System.Runtime.Fx.IOCompletionThunk.UnhandledExceptionFrame(UInt32 error, UInt32 bytesRead, NativeOverlapped* nativeOverlapped) in C:\Projects\dotnet\wcf\src\System.Private.ServiceModel\src\Internals\System\Runtime\Fx.cs:line 485
   at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pNativeOverlapped)

Repro here:
https://github.com/ssa3512/wcf-reliable-sessions

With service host project running
dotnet run -f net472 --project .\wcfasynctestclient\wcfasynctestclient.csproj succeeds
dotnet run -f netcoreapp3.1 --project .\wcfasynctestclient\wcfasynctestclient.csproj fails

Am I missing something?

Originally posted by @ssa3512 in https://github.com/dotnet/wcf/issue_comments/708584592