Find My Phone Server Unavailable?

Hi

I am suddenly unable to use Find My Phone on my iPhone 11 Pro. I get a pop-up message that says

"Find My Unavailable - Unable to connect to server, Please try again later."

It has been like this for a week. I have rebooted (didn't help), updated to iOS 13.3.1 (didn't help) and signed out and back in to my Apple ID. This did actually refresh locations right after I signed back into Apple ID, but then it stopped again. My own location is on and I can see my phone from my other devices, but I can't see the location of my other devices from my phone. All locations were updated at exactly the time I signed back in today (about 3 hours ago), but refuse to refresh.

I had no problems previously, and then location updates just froze on 30 Jan 2020. Any advice on how to fix this?