I finally found the best way to get it to work with 100% success rate to open or close!
- Don't just swing your leg on the ground, lift your foot as if you are going to kick the bumper. No need to touch the bumper with your foot, but as your foot gets too close to the bumper, the sensor will see it and will open or close.
This works 100% on the left side (midway between hitch and left end of the bumper). It also works on the right side, but with lower success rate!
Hopefully it works for you. We actually live this feature and use it all the time.