Apple Watch Series 8 Photos Watch Face not updating photos

The fickle Photos Watch Face: Some days it works absolutely brilliantly, delivering me newly selected pictures of my loved ones perfectly cropped and with the time placed in a pleasing position... all automatically. It's truly one of my favourite things about the Apple Watch.

However on other days it only has the first picture it ever selected, just that one. And there's no force refresh to populate the images, short of deleting the watch face and starting again I suppose, but then the cycle starts again.

Apple Watch Series 8 - WatchOS 11.6.1