It seems to just show you the largest set (50? 100?). If you delete them, then you will eventually show smaller ones once you get through enough of them.
Really wish there was a "delete all" or "select all".
Thanks. That makes sense. But I didn’t feel like deleting anything. Just my wife and I on the iCloud storage and there’s plenty of it at present. My photo collection that I’ve been cleaning up is a bigger offender right now than messages. Damn cats doing cute things.