iPhone 7 Plus not getting notification beep

I’ve been having this issue for quite a while now. I just suddenly noticed my iPhone 7 plus stopped giving me notification beeps despite all notification settings properly configured. I’ve read through solutions found online and after trying all steps, it’s still the same. The better solution I have experienced so far is that it’ll give me notification beeps for few minutes (max 1hr) and then it stops giving notification beeps again. Please let me know if anyone is experiencing this or has experienced it and what solution did the person arrive at? Right now my last hope is to restore factory settings but I’m still scared of losing apps and their data and at the end of the day, the issue won’t be resolved. I’ll be so glad if someone experienced can engage in this post.