Several stock Android users are reporting an interesting and somewhat amusing bug on their devices. The 'Until Next Alarm' option that appeared in the Notifications within the Do Not Disturb menu has gone missing, and no one knows why.
Actually, there is one theory, as one reader posted in the comments on Android Police. It's due to a bug in the method, which polls if there is an alarm in the next 6 days. When it calls roll(DATE, 6), neither the month nor the date get shifted to the next month, so if you're near the end of the month, it tests against December 1, 2015 instead of January 1, 2016. As such, this issue will get fixed next month but will repeat itself in the last six days, assuming Google doesn't fix it until then.
It's a small glitch in the implementation, but nothing to be alarmed about (sorry, couldn't resist).