I have about 64,000 photos and 500 videos residing in my Mac mini library. I’m backing these up to iCloud. There’s over 1 TB of available space in the cloud. But not all of my images and videos are being uploaded. 538 photos and 9 videos are tagged “Unable to Upload.” I looked through the photos, nothing unusual about the file types - mostly JPGs, some going back years. I did notice in some cases the image itself is grayed out but Info is still there. What’s that all about and how do I fix the syncing problem? Thanks.

Mac mini 2018

Sequoia 15.5