Certain apps do not give notifications

[AC Question]

I have an s7 edge and i am having notification problems. I have checked all settings, allowed all notifications, nothing is blocked, reset the phone (not factory), and it is still not working. Thankfully it is only certain apps that are having this problem. When i get a message on groupme for example, it does a sort of "half vibrate" or a "half ring" meaning it really only completes half of the assigned vibration or sound then it abruptly cuts off, and bam, no more notification. Only way to then find out i am missing a message is to go into the app. There are 3 or 4 apps that have been doing this, and it is rather irritating lol. Any suggestions?