Apple Clock App-Alarm

I have an alarm set on my phone through the Apple Clock app [it has a vibration turned on and a sound that can easily wake me up] . If I'm watching a Youtube video and turn the volume all the way down so I'm not waking up my wife or child, close out of the Youtube app, turn the volume back all the way up and have my ringer on and turned all the way up; my alarm makes no sound in the morning when trying to get up for work. Minutes/hours later, when I wake up and realize my alarm didn't go off, I pick up my phone and the alarm itself is displaying as it's currently going off. There is no sound and no vibration. When I check my volume again, it's still turned all the way up. I have tried the following things: deleting the alarm and setting a new one, reinstalling iOS, taking it the Apple Genius Bar and having them diagnose the issue, and even getting the Apple Store employee to get a replacement phone since he did not know how to fix the issue. This has now happened several times and has made me late to work on numerous occasions. After many times of being late due to having this issue, I have found the only way to fix this issue is when I'm finished watching Youtube, I have to shut down the phone and turn it back on or turn up the volume while having the Youtube app open and playing a video. I can then close out of Youtube. This has to be some type of issue with iOS that needs to be fixed. I'm sure there are plenty of people who watch videos on silent before going to bed, turn the volume all the way back up, and then the alarm makes no sound in the mornings.