[Elecraft] KX3 CW Muting on Strong Signal

[Scott Zastoupil]

During the Wisconsin QSO Party this weekend I experienced on a few occasions were a strong signal was near zero beat (maybe +/-50Hz or better), but all I could hear was "thumping" of the signal.  So these people were calling me, but I could not hear the 600Hz sidetone.  In order for me to hear them, I enabled RIT and tuned a few hundred hertz up.  I could see them in the passband of panadapter.
- Issue was with about 5 strong signals- Filter centered and 200-400Hz wide- Signal was visible near zero beat on NaP3 panadapter within pass band.  I/Q input to PC for visual spectrum only.  Not using audio from PC.- Preamp off in many/all cases on 40 meters.- Listening to audio via stereo headphones direct to radio.- Firmware updated last fall.
Any ideas or known issues in this scenario?

Scott, KB0KFX