"Messages on iCloud" grayed out on iPhone

Having the same issue except it’s across all of my devices!

When you look at your iCloud usage does it show that you have Messages stored in the cloud? Mine shows around 40gb stored and it's grayed out but ON with my iPhone. The Mac won't allow me to turn it on because there's an "iCloud error"

Sorry, didn't know anyone replied to my post (didn't receive an email or anything). Anyway, no, mine didn't show that but my solution was to fully wipe my iPhone and reinstall ios 11 then restore the new ios 11 backup of my iPad Pro (since my iPad would turn on "sync messages to icloud" just fine) and that did it. It was a royal pain since I have to further tune my iPhone back to how it used to be but luckily I keep both relatively the same and I'm pretty used to doing that from prior ios beta and jailbreak experience on previous iPhones. My Macbook Pro eventually allowed the setting to turn on and when i updated my Mac Mini, it also wouldn't turn on "sync messages to icloud" however it was actually giving me an error so I let it sit for a couple days and just tried to turn on the setting again today and it turned on instantly. So my guess is that it took my Mac Mini way too long to actually connect to iCloud fully but eventually it did and the "sync messages to iCloud" setting will now turn on. I don't know why my iPhone "sync" setting wouldn't turn on... I'm just glad I thought about restoring my iPad's backup (had to do that in the past and fixed the issue I had back then).

Funny quirks but messages on 100% of my devices are all syncing to iCloud now so TOTALLY worth it. If only WatchOS had this feature.

HAving the sameness issue all frayed out on three of my devices. Updated to latest beta and still same issues.

So I tried this and it looks like in order to get it to sync up you have to enabled two-factor authentication on your account.

Since it's on the cloud now it has to authenticae that it's you to give you access to everything on there. Not sure if they'll change that later on but it makes sense as to why they'd make it that way.

My sync seemed to be working but confused as to the core functionality. I see that deleting a message/thread on one device now deletes it on all. Are these now gone for good and not in the cloud? If so, I truly f’ed up.