Some early TWR-K64F120M Revision B boards were shipped with incorrect jumper configurations and demo application.
Jumper settings should be:
Updated application demo code and Quick Start Guide can be found at https://www.nxp.com/TWR-K64F120M
TWR-K64F120M boards with updated jumper configurations and demo code will be tagged with a label marked TDA4906 on the bottom side of the board.