Sub-orchestration's FunctionFailedException.InnerException.Message is always the "Exception of type *** was thrown"

[Meadow201317]

Issue
I am throwing DiskOperationFailedException() from the activity to orchestrator and expecting FunctionFailedException.InnerException to have the customized exception message, instead of the common "Exception of type 'Microsoft.CloudManagedDesktop.DiskRM.Core.Model.Exceptions.DiskOperationFailedException' was thrown.".

Expected
FunctionFailedException.InnerException.Message should be the customized Message.

Additional Details

In Activity
throw new DiskOperationFailedException("Failed to call ARM client").

In Orchestrator

catch (FunctionFailedException ex) when (ex.InnerException is DiskOperationFailedException)
{
    DiskOperationFailedException exception = ex.InnerException as DiskOperationFailedException;
    DiskActionLogging.Exception(this.logger, $"{exception.Message}, should set action as failed.", exception, actionPayload.Content, payload: JsonConvert.SerializeObject(actionPayload));
    await this.CompleteActionWithFailedReason(orchestrationContext, actionPayload, GetErrorCode(exception), exception.Message);
    return;
}

I wish to take the ex.InnerException.Message as "Failed to call ARM client" but the actual result is "Exception of type 'Microsoft.CloudManagedDesktop.DiskRM.Core.Model.Exceptions.DiskOperationFailedException' was thrown."