Not sure if i do it right but when i double tap the watch, nothing is showing up. i have to do it a few times for the digital time to display. I also have the gesture on only when i exercise. Could it be a hardware defect ?
Tap hard with your fingernail right above where the "6" would be. I ran into the same problem thinking just feeling my skin would activate it but it doesn't. There is also an earlier post about this for more info.