I've had my PS4 since launch, having previously been exclusively an Xbox 360 owner during the last console generation. At first I thought that Sony consoles simply didn't tell you when people on your friends list hopped online. Then I bought a PS3 and saw that console notifies you whenever your friends come online, and also when they go offline. Finally, several times I noticed my friends inviting me to a party within moments of starting my PS4, so I asked them how they knew I just hopped online, and they confirmed that notifications seem to be working fine on their system.
I've looked at my notification settings, and literally every option has a check mark by it. Is there something else that I might be overlooking? Has anyone else here had this problem and perhaps understand how to fix the situation?