Yes! I posted about this a while back! It's been happening for months since iOS 8 in September I think. Really annoying as I often rely on that sound to confirm the photo is taken if I can't see the screen etc and then I have unwanted photos because of it.
Not as common but I sometimes don't get the lock sound when locking my iphone or iPad and not and then I don't get the text message alert sound I just happen to see the screen light up to know I didn't get the sound alert.