Issue has been resolved! I had Substratum Theme and Andromeda and a theme on so I uninstalled all overlays and restarted my phone. Now my notifications for Snapchat are showing and sounding.
None of them hjelp in fact none of the YouTube blogger help either. The one and only solution is ; remove LOCK IT app and the issue is solved immediately. And enable all notification in app and in the mobile.... Good days