MacOS contacts photos not showing

Photos of my contacts are not showing on my Mac. They are still showing on iCloud.com and on my iPhone.

I tried these things which did not help:

• turn off/on iCloud for Contacts. Close/reopen Contacts. Reboot. In varied sequences.
• updating a contact on my Mac.
• updated a contact on iCloud.com

I tried this which helped a little:

• Updated a contact on either iCloud.com or my Mac: the picture for that one contact then showed up on my Mac, but not for other contacts.

So there is a connection between my Mac and iCloud.com.

Help!