BonFire501

I know I'm replying to a pretty old thread but I just purchased a used 2014 GMC Sierra with the same issue. Thing I thought was strange is that I test drove a 2015 prior to buying the 2014 model and the 2015 had a "browse by folder" USB option and the 2014 does not. Is there a firmware update I can somehow upload to my truck to get that same capability. Seems odd that the aftermarket JVC head unit I installed in my 1995 Honda Accord back in 2006 handled this and my 2014 GMC Sierra can not.