A few weeks ago, after installing build just before win 10 mobile 10149 in my lumia 830, I noticed the three capacitive buttons worked intermittantly. I have no screen protector on my phone. After a few days, I had to resort to scrolling up and down on the screen I was on then hitting which ever capacitive button I wanted. That worked. After installing build 10149 the capacitive buttons ceased to function no matter what trick I did. I reverted to wp 8.1 but the problem still existed. The phone is still usable on wp 8.1 since there are ways to revert to your home screen. Since I installed build 10166, there is presently no way of moving from one screen to another app without the use of the capacitive buttons. Sadly they no longer work.