Apple Watch Series 6 phantom chime

I purchased an Apple Watch Series 6 on May 1, 2021. Approximately two days later, a phantom chime and vibration would occur every 30 minutes or so. I visited this site and found no solution(s). I checked Settings > Accessibility > Chime, I checked notification settings on the watch and my iPhone 12 Pro Max, and everything else I could think of. I finally erased the watch and repaired it with my iPhone. That worked for about a week and the watch started the phantom chime/vibration again this afternoon. Help!