Why don't I receive notifications from certain apps?

[AC Question]

The other day, I went to the Cubs game and put my phone on ultra power saving mode. When I got home and turned it back off, my phone syopped giving me notifications. I get them from Facebook, Twitter, and instagram, and Snapchat. But for ESPN, MLB At Bat, The Score, and other sports apps I get nothing. But the notifications on those apps are all turned on.