I deleted the cache on my phone, but didn't delete the data. I did uninstall and reinstall, but perhaps that did the same effective things as deleting data. Now all seems to be working OK, albeit a bit slow (as could be expected at the moment).
Rescue call page now opens OK and still shows UK number.
The maps section looks a lot cleaner, and you can edit the POI list.
I enabled the biometric option - when I had to set something (I think it was to enable the digital key) it popped up the fingerprint login prompt and that worked OK. I'll leave things for a while and see if I'm given a login prompt when I open the app again, and what form of prompt that is.