Big Sur won't sync with iPhone 7 [View all]

Ever since I upgraded to Big Sur, I've had problems syncing my iPhone with my iMac desktop. Originally, it seemed that the only thing that wouldn't sync was Contacts, but now nothing will sync. The iMac recognizes the phone and backs it up, but I keep getting the error message that the iPhone failed to sync because the "sync session failed to finish."

I also have an iPad Pro, and it syncs just fine, so I'm wondering if it's just that Big Sur hates older technology.

All the software is up to date on both iPhone and iMac.