Hi I have a 2016 Chevy Maibu 31,000 miles. I’m occasionally hearing a knocking noise coming from the rear when the car starts back up from the auto stop feature. It’s been to the Chevy dealer and they can’t figure it out as it doesn’t do it all the time or when it should (when it’s at the shop). Can anyone help me or give me some advise? I don’t know what to do cause it’s so frustrating. Thanks in advance