Did you expect them to be automatically opened and loaded on your other device? That would not make much sense if you're syncing your laptop with your phone. Most people use a lot of tabs on desktop and a phone wouldn't cope well with that and you probably don't want all the desktop pages loaded anyways.
The way it's meant to work is that you sign in to opera sync on both devices and then you can chose to open tabs that you have opened on other devices.