HD voice was working on my nexus 6 for over a year but it recently stopped. There used to be an option in Settings -> Wireless -> More -> Cellular networks -> Enhanced 4G LTE. That menu item is no longer there. The *#*#4636#*#* menu says "Turn off Volte Provisioned Flag", which means that it's on, but clicking that button no longer does anything.
I tried removing and re-adding HD voice from that line through myverizon but still no luck.
Anyone encountered and fixed this?
I am still on 6.0.1, MOB31K.