Sadly, I have now had the problem twice. I did the dreaded factory reset and it all came back for a week. Aside from the hours it took to make the phone "perfect" again, I was happy! Not so fast! Back to silent notifications. If Samsung can't fix, maybe Google can build a patch. Millions of factory resets cannot be good for business.
Hit your volume button up or down and you will see the ringtone volume. When that pops up, there is a down arrow on the left hand side. Click on that to bring up all of the individual volume controls - ringtone, media, notifications, system. Hope this helps. I tried everything else before i found this and it fixed my issue