Audio off whilst using ipod nano problem via USB

[Becci]

Hi, this problem may have been mentioned before but i currently have a 2014 icon plus. The ipod sound isn't great with the aux in cable so i prefer to use the usb connection instead. However it seems whilst driving if the ipod reaches full charge it turns the stereo off completely and Audio off is displayed. When i switch the system on if takes a minute for the ipod to register again. And when it does it starts from the beginning of the play list. Its not a huge problem but it very annoying. I know i should just use the aux in but the sound quality is poor. I cant seem to rectify this problem. Looked thru the settings for both the stereo and ipod. And nothing. If i use my iphone 5 via bluetooth the stereo doesnt turn off at any time and i dont have a problem at all. Can any one help?