Same issue here....
I feel the same exact thing in my 2015 LT 1.4, and every time I take it in to get it looked at, it's always "We couldn't find anything wrong with the transmission and it's just the nature of these 6 speed transmissions." I've had nothing but odd conditions happening with my auto transmission (UNSAFE surging at stop lights/signs, very hard downshifts, some kind of slamming feel when I let off the gas then attempt to speed back up again, the transmission causing the engine to rev really high when going less than 15 mph-almost as if it was in way to high of a gear and it shouldn't be), and like I said, there's NEVER anything wrong with it and there's never any "codes" in the computer. But yeah, I can feel the surging feel when I'm going down the highway at a crushing speed. I thought maybe it was the a/c compressor, but that proved false as it still does it even with the a/c off. NEVER have I ever felt an automatic transmission act so quirky and unpredictable. IF I think about another Sonic when my lease is up, I'll DEFINITELY be getting a manual transmission! Good luck getting the dealership to help you out too.
