Sync photos to iMac stopped

Upgraded iMac to Os 10.13.2 on 12/7. On 12/12, photos stopped syncing to mac. Photos will sync to iPad, iPhone X, even my old 6s, but cannot get sync to iMac. All iCloud are set to same ID and passcode. Need to get photos to iMac for editing. All photos are in iCloud.com, just not on iMac.

Any suggestions or thoughts? Thanks,

Joy