I cant be the only person this is affecting, I've searched a few times to no avail. Whenever I am using my Mac at my desk I stop receiving notifications on my iPhone. If I receive an iMessage it will pop up as a notification in the upper right hand of my Macs screen as its supposed to. The problem is I'm not always actively at my desk even though I may have the display active. Therefore I've sometimes gone hours with someone trying to reach me and I was none the wiser since I never received a sound/vibration due to the computer suppressing the notification sound. It would be nice if my iPhone alerted me regardless and if those messages remained on the lock screen instead of disappearing since i technically "saw" them on my Mac. Maybe I am just unaware of a simple setting but this has been driving me crazy for a long while now.