Security updates happen monthly, you should get it in the second or third week of the month. Google never gives a schedule for updates, major or minor, they happen when they happen. The security updates also contain bug fixes. Android N is in Preview 3 which is Beta 1 (previous two were Alphas). I've been using N since Preview 2, Preview 3 is pretty solid, Preview 4 is due in a couple of weeks (but once again no promises for Google, could be earlier or later). Give N a try to see if it fixes your problem, if it doesn't then send feedback from the phone, now is the time to get Google to pay attention.