My Notifications Aren't Working.

[Fattz]

I just did a software update on my Note5. Ever since then, I've been having 1 problem after the other.
First I had this notification saying that Google Play Services wont work unless I update Google Play Services, after I updated that I stopped receiving any notifications and my apps have stopped working unless I physically open an app.
Like WhatsApp for example, I won't receive any messages, neither will any messages go through unless I open WhatsApp. It's so ridiculous because I use WhatsApp on my laptop as well for working purposes and it won't connect to my phone unless I open WhatsApp on my phone. Any help would be appreciated.

 

[Trees]

If you updated to Marshmallow, think it changes the way that notifications are managed. Are the notifications not appearing in the notification bar, or on the lockscreen?