Find my friends no longer updating so frequently

I have used FindMyFriends regularly on ios and Mac OS. It works and often you can see "Live" and "Now" progress of friends. However now I can't reliably see their live or now position - often it will show 45 minutes ago and not refresh. Auto updating doesn't seem to work as it used to. If I shut down the app and immediately restart it then it will immediately show the Now position - why is that? Why does it require a restart to force it to update from 45 minutes ago to now? The same issue occurs in Mac Ventura and in iOS 16.4.1

Even when I restart the app it will show Now but I am flummoxed as to why it does not show Live. What determines when Live is shown as opposed to Now? Previously I could track the live motion of a car reliably - now, I hardly ever see Live.

I have checked background refresh is on, Low power mode is off, all OS are uptodate (that prompted the issue!), and that the various tracked devices are as they used to be when it worked fine.