A couple years ago my dealer advised me the problem is not that the cancel button is insensitive, but rather that the on switches are over-sensitive, so as you cancel the signal you often turn it back on as the switch slides a bit left or right... The harder you mash the cancel button, then, the more likely it is that the blinkers keep going!
The problem can be mitigated by adjusting your technique: Press the button lightly while taking a bit of care not to jiggle it left or right.
After following this advice I never had this problem again
