MIB1 to MIB2.5 upgrade completed, I have "full" functionality, except no sound...I read in the forums this is common, but cannot find the solution. I have a NAR 2015 VW Golf TDI SEL w/Fender, the new Unit "Unlocked" MiB 2.5 Discover Pro 9.2. Could you help with the "no sound" issue? Also, what...