Enable messages in iCloud not showing up as an option

Recently my Messages syncing stopped working on my Mac. After investigating, I don't see the option and check box to 'Enable messages in iCloud' or the 'Sync Now' button.

I am running Monterey 12.4 and iOS 15.6.

I have restarted both phone and Mac.

I am signed in to the same Apple ID on both devices.

I have two-factor authentication turned on.

I have Keychain enabled.