I’m trying to upload files to iCloud and in finder, it says "icloud not syncing" and that "there are pending items to sync".

I’m trying to upload files to iCloud and in finder, it says "icloud not syncing" and that "there are pending items to sync".

 I restarted my Mac, then I restarted in safe mode, then I reinstalled the operating system, and none of those things fixed the problem. Then I tried to disable iCloud from System Settings, but it says "iCloud Drive needs to finish updating before being turned off" and I'm scared that all the documents that I just tried to upload will be lost in the process.

This whole problem started when I tried to upload photos. I tried to drag and drop them from a flash drive into the Photos app, and it looked like everything was working fine but nothing was happening and no photos were added. Then I tried to drag and drop them into iCloud.com in Safari and received an error message that said items in folders couldn't be uploaded, even though I was only uploading JPEGs and nothing was in a folder. Then I tried to do the same in Chrome, and some more were added but the remaining items said "the dimensions of the file are invalid." I've spent DAYS trying to upload these photos, and it is absurd that NONE of these solutions are working. Especially because I pulled them from my older Mac and they were loading just fine in iPhoto.

Please send me a solution that will actually work.