In reply to no_more_scotch_eggs:
Presumably your not up to your iCloud storage limit as Apple prevent further transfer if you have. They insist on storing a copy in the cloud. If over, they don’t delete anything (IME) unless you switch off one of the sharing settings. If you are over the limit be careful that you have backups as if not you will have to watch Apple remove all shared photos (or whatever is in the cloud) and delete them on the other devices (still should be stored on the original device IF you have set it to retain original ie NOT using the optimise storage setting. Deletion with me has been an all or nothing of shared stuff. Frustrating I could not select what to allow them to delete so had to wait till I had time at home to start over again, twice!
Back to basics. Did you reboot after correcting the account problem? Switch off sharing photos (provided you have all your backups done), switch off upload to iCloud and my photo stream, etc and reboot (both devices). You may have to re enter cloud ID. Switch all the usual photo setting for iCloud back on.
Twice done this due to storage limit breaches, and when I switched back on to upload the photos, it was automatic and I could see the individual photos arriving onto the iPad in real time.
If this does not work sounds you have a conflict of settings between the devices, and you may have to go back to factory settings to wipe what is wrong. Sorry beyond that is more than my knowledge.
