Newly upgraded iCloud+ not syncing photos
I have an iPhone 7+, running on the most current ios. I've never paid for extra iCloud storage, so my iCloud has been full for ages now using the free 5GB, with constant messages telling me it's full and not backed up. I plan on upgrading phones soon so today I upgraded to iCloud+ with 50GB of space to backup my photos. I only have 4,882 photos on my phone.
When I go to my photos it says "3,863 items have not been uploaded to iCloud - Manage - Not enough iCloud Storage" However when I go to my iCloud settings it says I have only used 5GB of 50GB - so it is not syncing my photos, and when I log into my iCloud it is only showing the photos that were synced before I purchased iCloud+.
In the same settings it is turned on to sync my photos to iCloud, with download and keep origionals selected.
Can someone please help me figure out why it is not syncing my photos after purchasing iCloud+? I tried restarting my phone and it still isn't working. Is there a way I can make it manually sync the photos? Thank you!
iPhone 7 Plus, iOS 15