calls are not ringing while on facetime

When people call me through WhatsApp or the regular phone app and I’m on a FaceTime call, it does not show a missed call notification or an incoming call. It also does not ring or vibrate. I have silent mode off and have no do not disturb/focus functions on. I only find out about the calls when they tell me (in real life) that they were calling me and I did not answer. The calls are shown in Notification Center, however, I am not given a notification for them. Is there any way to solve this in settings? It is a very important issue for several reasons related to family.