Rear defogger not working but mirror defrost works,same switch.

Hello, The rear defroster may be malfunctioning because of that portion of the switch, a fuse, or loss of connection at the window. All three are fairly common. The Nav unit may not be able to display data because of a missing information, or a bad connection to the antenna. There also may be issues with the body control module, which will disallow random components from functioning properly. Being a 2014 model, you should be able to get these items covered under warrant, no?