Venu SQ Heart Rate Stopped Tracking Higher Intensity Exercise

My Venu SQ has stopped heart rate tracking when higher intensity work is done. The higher intensity is power walking (about 55 minutes) that raises my heart rate into the 140 to 150 range. My Venu SQ will not get above 100 during the exercise. This has just occurred in the last several weeks. It seems to work fine for lower intensity, rest, etc., but doesn't seem like it can handle the higher intensity work. The Garmin app shows a blank spot on the heart rate timeline during the higher intensity exercise, then picks up the heart rate when the level gets below 100. So both the Venu SQ and the app are showing the heart rate issue.

I've tried resetting my Venu SQ before I exercise (full reset), even during the exercise when the heart rate does not seem to be functioning. I clean the backside sensors with a dry cloth after exercise as well.

Is there a sensor setting that I'm missing? Is the heart rate tracking sensor shot?

Will appreciate any input.