I actually get very few phone calls, but at some time in the last couple of weeks or so I've stopped getting notifications on my 645M when the phone is ringing so that I can identify the caller. All other notifications are working, including ones from the Phone app such as "Missed call." My phone is on 5.70, but I think that was a very recent update and they were also not working on 5.60.
One complication for figuring this out is that I just got a new Pixel 3a a week ago, replacing my Pixel 2, and unfortunately I can't recall if I've ever received a phone call where the notification worked since I got the Pixel 3a or if it stopped working when I switched phones.
In any case, is there any setting I might have missed that would affect the incoming call notifications only?