I bought the S10 a few days ago. Messages work fine with sound and edge lighting. Viber works fine as well. Messenger app works with sound (but not lighting but that's normal).
Facebook doesn't want to play nice. Sometimes I get notifications, sometimes I don't. Sometimes I hear a sound. The edge lighting refuses to work. Is it a problem with the app or with the OS? I don't use custom apps for lock screen or edge lighting, the only custom app I use is Nova Launcher Prime. Am I missing something folks? I've changed so many settings these past few days trying to fix it, I don't even know if I made it worse or not.
I allowed the notification bar to show all notifications instead of just a few. I also reset my phone as I'd only had it a few days at that point so wasnt a bit deal. Also, try setting it so the badges dont show the number. I did this and it started to work then changed it show the number of notificaions again with no issue.