Call alerts on MacBook Pro without Caller ID post macOS 15.1.1 update

Until a couple of days ago, which I think is when I upgraded to 15.1.1, all incoming calls to my phone would pop up on my Mac screen too and I would be able to answer them there. Since my headset can only connect to one device at a time and I can't handle long calls holding the phone to my ear, that was crucial for me.

Now suddenly, I'm not seeing any pop-up at all. The calls (and this includes calls on apps such as WhatsApp, RingCentral etc.) are still coming in to the Mac and I can answer them by pressing a button the headphones, but I don't have any idea who is calling (unless I have my phone close at hand) and like everyone these days I am selective about which calls to take. And the button doesn't always work. The connection to the headset is fine - I can make outgoing calls with no difficulty.

I've checked settings in Notifications etc and everything looks fine to me (and it was all working until a couple of days ago).

Any suggestions please?

[Re-Titled by Moderator]