Thanks to Bill Somervilles’, G4WJS, insightful and detailed analysis of the .wav files I sent him I’m back on the air. For reasons yet unknown the audio seen by the decoder was LSB where the various digital modes require USB.
How this happened is undetermined. My transceiver indicated it was in USB mode as I had been for a very long time never having been turned off. Selecting LSB mode the audio signal on the waterfall disappeared as is expected. Selecting USB mode the waterfall again was active … and decoding began, a puzzle.
I forgot the most basic troubleshooting technique, turn it off then on again. :-)
Thank you Bill for your patience.