iMessage opens the wrong image

This has been discussed at length before, seemingly with only inadequate responses. Just reporting that I happened on the solution with a web search of a related question : "how to sync messages in macos". Miraculously, that produced advice "go to System Settings -> <your icon at the top> -> iCloud -> Show More Apps -> Messages in iCloud -> Sync Now." Syncing had last happened automatically four days ago even though I'd been using the phone where the image originated and the laptop almost constantly on those days. After that fix, the correct image is loading!

It has sync'ed from the phone to icloud, but not from icloud to the Mac. Same thing happens with Notes.

I see the statement "syncs every time you make a change such as adding a contact, editing an event in calendar or adding a photo to iCloud photo library". Okay, it did that, but what about syncing by downloading to the next device that I use?