iCloud Photos on Mac not syncing
I have a large collection of photos and videos, roughly 32,000. I recently signed up for 2 TB iCloud storage to be able to have them backed up to iCloud. I have a MacBook Air m1 with a 256 GB hard drive. I created a photo library on an external USB drive formatted in Mac OS Extended format. I copied the directory with my photos and videos into the photos app on my MacBook, one folder at a time (each folder has a year of photos). Everything successfully imported to the library, and duplicates were identified and merged. I have iCloud photo syncing on. I set this library as my system photo library. The library file on the drive is about 400 GB right now and I can see all of my photos and videos. But they are not being loaded to iCloud. It has just sat at "Syncing 31,365 items to iCloud" for hours and now days, with no progress. I cannot see any progress when I look at the library on iCloud.com or in my iPhone. I am using the correct userid, and I have made sure all syncing options are selected. I have restarted the photos app, the bird process, and the laptop itself many times. The drive led blinks and I can hear it spinning, but nothing happens. I have searched multiple forums and tried everything to no avail. Any help is appreciated, thank you.
MacBook Air (M1, 2020)