Unable to Upload to iCloud (photos)

Hello, I have been trying to get all of my photos to upload to iCloud for over a month now. I have a folder of 2,500 photos that are “Unable to upload to iCloud”. These are all original photos and videos taken on my iPhone camera, unedited and no third party apps. I have plenty of space available in my iCloud. The range of dates of the photos that are unable to upload are anywhere from 2 years ago to 1 month ago…I feel like I have tried everything and I am frustrated there are so many photos unaccounted for when paying for iCloud. Can someone please help me get all of my photos onto iCloud.