RTOS/CC1350: HwiP_disable() function hangs the RTOS code on cc1350

Tool/software: TI-RTOS

Hi,

For a project we have an msp430fr connected to the cc1350 uart. To flash this msp from the CC1350. To do this I've ported the "CC2640R2Host_UART_BSL_MSP430FR" example, but I'm running into a problem.

When writing the password through UART, it calls an UART_write:

UART_SendByteArray(sendBuffer, PASSWORD_LENGTH + 6);

//*****************************************************************************
// Send byte array through UART ***********************************************
// byteArray: the array of the bytes to write *********************************
// size: the size of the data array *******************************************
//*****************************************************************************
void UART_SendByteArray(uint8_t * byteArray, uint16_t size)
{
    UART_write(uart, byteArray, size);
}

And in the UART_write functiojn it calls the HwIP_disable() function but then it hangs and doesn't continue.

    /* Disable preemption while checking if the UART is in use. */
    key = HwiP_disable();

The code is in the UARTCC26XX.c and this uart works fine on another firmware for this chip.

int_fast32_t UARTCC26XX_write(UART_Handle handle, const void *buffer,
        size_t size)
{
    unsigned int                    key;
    UARTCC26XX_Object               *object;
    UARTCC26XX_HWAttrsV2 const     *hwAttrs;

    /* Get the pointer to the object */
    object = handle->object;
    hwAttrs = handle->hwAttrs;

    /* Check that there is data to write */
    DebugP_assert(size != 0);

    /* Disable preemption while checking if the UART is in use. */
    key = HwiP_disable();
    /* The UART TX is disabled after a successful write, if it is
     * still active another write is in progress, reject. */
    uint32_t writeActive = HWREG(hwAttrs->baseAddr + UART_O_CTL) & (UART_CTL_TXE);
    if (!object->opened || writeActive) {
        HwiP_restore(key);
        DebugP_log1("UART:(%p) Could not write data, uart closed or in use.",
                    ((UARTCC26XX_HWAttrsV2 const *)(handle->hwAttrs))->baseAddr);

        return (UART_ERROR);
    }

We're using the latest "simplelink_cc13x0_sdk_2_30_00_20" and "tirtos_builds_CC1350_LAUNCHXL_release_ccs_2_30_00_20", but with a custom board. 

What can this be??