Verizon Samsung 7 able to make/receive phone calls, but no data availability on at&t

[AC Question]

I recently purchased a Verizon Samsung S7 (SM-G930V) and installed my at&t sim card. Although I'm able to make and receive phone calls as well as messages, the data is not working, not even showing next to the coverage bar. I have added and configured a new access point, talked to my carrier (att), and nobody seems to find a solution. My phone does not update it's software either; I had it flashed to its latest software update, but no change in data availability. Since it's an American version i haven't been able to root it. Please help, I don't know what to do at this point!