@Eric Schoen Thanks for the question. You can get the result from a single channel audio, otherwise remove the below 3 lines of code in the sample code link.
You could find the current SDK sample code in the public document, just adding 3 line of code (yellow highlighted and bold) to support single channel audio.
// keeping these lines here for single channel audio
var connection = Connection.FromRecognizer(conversationTranscriber);
connection.SetMessageProperty("speech.config", "DisableReferenceChannel", $"\"True\"");
connection.SetMessageProperty("speech.config", "MicSpec", $"\"1_0_0\"");
// end