Part of notifications arent shown at all

I am using the app on iPad Air with the latest iOS. I am using Alert notifications for new emails but they arent shown periodically. So I miss new emails till I manually check them in the app. Please fix this problem. I just selected AOL iOS app for this feature because it shows alerts with sounds as I need.

Lenorik Molik about AOL Mail, News, Weather, Video, v4.1.0