My Series 3 watch is connected to AT&T cellular. I leave my phone at home and turned on, and then leave the house with my Series 3. I can connect to LTE fine, and calls work great - I've had conversations on the watch. I have not, however, ever had any semblance of data working on the watch when on cellular. No iMessages have come through, no apps have been able to pull data, and I have never been able to "talk" with Siri. Has anyone had this issue?