Hi, I have 3 devices (iPhone, iPad and a 2017 MacBook) where iMessages in iCloud is working perfectly (sync/delete across all devices). I recently started to use my old MacBook Pro as a media center / NAS / spare machine. I decided to log in into iCloud with that old machine because well, it's convenient to have everything synced with your other devices. Every iCloud service (Safari, Calendar, Contacts, Photo library, etc) seems to work fine on that old MacBook Pro except Messages in iCloud. At first, the messages were downloaded but I've noticed that some were missing compared to the other devices, so I've decided to deactivate Messages in iCloud for that MBP, erase everything and reactivate again to try to do a proper sync. The thing is that, since then, I can activate the service but even if I press the "synchronize" button (see the screenshot), nothing happens. The button is greyed out for a few seconds and then become clickable again. So on that 4th device, I am stuck with an empty Messages app which does not seem to want to download any message from iCloud. Everything is still fine on the other devices. (the service is not activated in the screenshot but I am just using it to illustrate the button I am speaking about) I have tried to log out / log in from iMessage, as well as from iCloud, but it does not change anything. It's like the app can do a sync the very first time you activate the service, but then, never again... Thanks for any help or advices, oMc --- Post Merged, Jun 12, 2018 --- I just want to add that any new message will sync perfectly to the old device and will be deleted too if I delete it from any other device. It's only the message history that doesn't want to be downloaded to this old device.