Glitch in receiving Notification ??

I am having this problem since many days ago … it just irritates me and sometimes frustrating too .. i am asking today because now its happening again and again and again … 

Problem is that i have a lot of notifications in my notification centre but that bell icon doesn’t inform me because that 🔴  is not showing on bell … it disturbes my engagement … why this happens  i am seriously hating this issue … did this happened to any of you ?? Can any one tell me why this happens????