I'm running the nrf5340_audio application on the nRF5340 Audio DK and have a UART wired to TP60 and TP61. As long as I have USB (onboard j-link) or my Segger j-link connected to the DK the UART shell works fine. However, when j-link is disconnected the UART stops working until j-link is reconnected. My prj.conf has the following:
# Console related defines