No camera shutter sound on first shot

I have an iPhone 6 plus 128gb silver. I noticed that there is no camera shutter sound that plays whenever I take pictures on the first shot but only happen if I havent used the camera for a while; say an hour or two.

I've turned the phone off/on and reset but still does the same thing.

Abyine else having this issue?

I've also noticed that sometimes the text/ringtone doesn't play when I browse through text and ringtones.