I just upgraded to an iPhone 8 from a 5s. I have photos of those listed as my favorites. Some of the photos won't stay with the associated contact. I open the contact, tapped Edit, Add Photo-> Choose Photo, pick the picture I want, tap Choose, then Done. About 5-7 seconds later, the photo disappears.
My phone and desktop use a Hosted Exchange for mail, contacts, notes etc. I don't use iCloud. Any ideas? DB