I have the same question. I have managed to set up the passenger mirror to dip in reverse, although the process to do it was a total pain, but it doesn't seem to work on the driver mirror
Same for me, only the passenger side dips (occassionally) and I find I am constantly having to re-adjust the passenger wing mirror when I get in the car (not the drivers side)
When set up correctly the left mirror will dip when selecting reverse if the mirror adjust knob has been selected to left side. Then the mirror will return to normal position after you drive forwards above about 5 or 10 mph, OR if you turn the ajust knob back to centre position.