iCloud Backup gets Stuck / hangs and Photos not being backed up after upgrade to iOS 13

After upgrade from 12.4.1 to iOS 13 (which went fine, no issues).....

when attempt backup (on phone /WiFi), it says “backing up”, then it says “updating iCloud” 1 min. remaining. It hangs there for many hours, twice overnight. Never finishes.

When I then tap the back button to go to the previous settings page, then go back to backup page, it then shows last successful backup time, corresponding to time I did the backup (not including the hours where it was hung up saying “updating iCloud”).

When I then look at the size of the backup, it is far too small, by the amount of my iPhone

photos. I previously backup several times a week for years without this issue. I am well aware of my photo library size (1.2GB) and typical total backup size (1.6GB). But now my backups are only 350MB. This is far less than my photos alone.

Notes:

• I do NOT use iCloud photos. Never have. It is turned off. Therefore, the photos should be included in a regular backup.
• iCloud/manage Storage/backups/my phone/choose data to backup Photo library is on.
• My iPad (iOS 12.4.1) has identical settings and it backs up fine, including it’s photos.
• I have the 5 GB iCloud storage. The total size of my backups (iPad plus iPhone) is expected to be about only 2 GB (with the iPhone photos, ie the backups I made on both just few hours before updating iPhone to iOS 13).