He guys, new to your community. Just thought I'd add a little something here to contribute. I have a 2016 Enclave. It has 76k miles on it. Just bought it used from a dealer. About a week or two after I bought it, my wife started noticing a shutter (which I also felt) when accelerating around a corner. Seemed very intermittent and only when the trans was shifting from 1st to 2nd gear. Fast forward 2 weeks from there, the transmission now has only forward gears! It drives forward in Park (yes park), Reverse, Neutral, Drive and Low. Called the local buick dealer, they said no manufacturer warranty or safety recalls open on my vehicle. I am now working with the dealer that I bought it from who seem to be very willing to want to make things right. I just had it towed to a local GM dealer and am waiting to hear what the diagnosis comes back as. I will keep this post updated.