iMessage Not Syncing When Mac Asleep

When the Mac is asleep, all operations get suspended, i.e., no activity, even sync, will happen. When it wakes up, that is when it is a hit or miss - I experience a similar behavior, but I just wait it out (it syncs eventually). Rebooting the machine, however, gets the Mac in a fully refreshed state (maybe it had a bad sleep? LOL) and immediately syncs. Weird, huh?

I think this is a bug on the Messages app on MacOS that needs to be fixed soon. At the moment, there is nothing we can do but report it and hoping that others will do, too.

Agreed it is definitely a regression. This is only a recent phenomenon.

I am having the exact same issue. Whenever I wake the computer from sleep mode, Messages do not sync for at least 20 minutes. This has to be a bug with the new Sonoma operating system 14.5.

This started happening to me when I upgraded from Ventura to Sonoma. Blue (imessage) messages that were sent/received while my macbook was asleep would sometimes take hours to sync after reopening my laptop.

I don't use "messages in iCloud"—never have—I don't have enough iCloud storage. That wasn't the issue. I did all the restart / sign in/out fixes that people have posted elsewhere—nothing worked.

Eventually I realized that this issue only happened when my macbook was closed AND unplugged—it didn't have any problem when it was plugged in. The fix, for me, was to disable "low power mode" completely (I'd had it set to "only on battery"). You may also have to set "wake for network access" to "always".

Hope this helps.

I just upgraded to Sonoma (late to the party, I know) but this is driving me absolutely nutty.

Thank you for this tip!

What fixed it for me was enabling Prevent automatic sleeping on power adapter when the display is off in Settings -> Battery -> Options. (The Options-button is at the bottom of the Battery screen, you may have to scroll down to reach it.)

More on my configuration: I have a MacBook Air that is connected to (and drawing power from) a Studio Display. The OS is Sonoma 14.5. I use Messages in iCloud and message syncing between devices was working great for me until a few months ago. (It could be that that was when I upgraded to Sonoma, I can't think of any other recent configuration change.) It basically stopped syncing when the computer was asleep. I was able to manually sync the MacBook with my iPhone by initiating a sync on my iPhone and then on my MacBook. But this is very cumbersome, because you have to do it every time the computer wakes up from sleep -- I was ready to give up on Messages on the Mac entirely. For what it's worth, I also have the following related settings:

Enable Power Nap: Only on Power Adapter

Wake for network access: Only on Power Adapter

Even if you have a different configuration than me you should try adjusting these settings -- perhaps they should be slightly different for different configurations, but I'm convinced the root cause lies here.

Good luck!