My 2018 Sierra Denali HD goes out constantly. It seems to be the same 10 stations but I can't keep them playing even staying still on a clear day. GM says it's satellite service yet the 2015 I traded, the 2018 loaner they have me in and my wife's 2016 Acadia do not have these issues. They have replaced my antenna but the issue persisted. GM is supposed to be sending a rep out but it will be weeks before he gets here. It's very frustrating.