Why don’t I get notifications when I get a missed call on iPhone?

Hello,
Whenever someone calls me or facetimes me and I don’t see it so it goes to missed call. But I’ll go on my phone then and I won’t get any notifications on the lock screen that I got a missed call. And there is no notification on the FaceTime app or phone app but in settings it says notifications are on. This happened on my old phone, then I got a new one and it was working for a little bit now I don’t get notifications again. What can I do?