I am logged into messages on my laptop with the same icloud account as I use on my iphone, and I can send messages both using my laptop via the app and through my cell phone, but the conversations don't sync. I can send messages from both to my contacts.
How do they sync up?
Your messages will synch between devices if you enable iCloud synch on those devices.
On your laptop, open the Messages app, click Messages > Preferences in the menu bar, click iMessage (top right) and check "Enable Messages in iCloud".
On your iPhone, open Settings, tap your name, tap iCloud and turn on Messages in the APPS USING ICLOUD section.
Your messages will synch between devices if you enable iCloud synch on those devices.
On your laptop, open the Messages app, click Messages > Preferences in the menu bar, click iMessage (top right) and check "Enable Messages in iCloud".
On your iPhone, open Settings, tap your name, tap iCloud and turn on Messages in the APPS USING ICLOUD section.
Try turning Messages syncing off, restart, and then try turning the Messages sync back on.
The solution suggested doesn't not solve the problem.
Trouble with messages app on laptop syncing with phone messages
