Hi,
It seems that the file describing the GPIO peripherals (msp430fr5994.h) shipped with Code Composer is broken - the macros, defining the existance of GPIO ports (e.g. __MSP430_HAS_PORT5_R__) are missing, causing the driverlib not to execute as expected (ignoring the request as the base_address returned by the GPIO_PORT_TO_BASE is set to 0xFFFF). Pasting the file from older Code Composer version fixes the problem.
Best regards,
Konrad