AWR1642: CANFD API: CAN messages not sending payload, terminating early, returning CANFD_EINUSE

I've been following along with the Unit test for the CAN_FD Driver, and as far as I know, I'm using the API correctly, however, when I try to send any number of bytes, the payload is not attached to the the CAN Message

    {
        const int CAN_PKT_LEN = 4;
        int errCode, retval;
        uint8_t canPkt[CAN_PKT_LEN] = {0};
        uint16_t temp = (uint16_t) ((rangeEst) * 1000.f);

        canPkt[0] = (uint8_t)(temp & 0x00FF);
        canPkt[1] = (uint8_t)((temp & 0xFF00) >> 8);

        temp = (uint16_t) (linearSNRest);
        canPkt[2] = (uint8_t)((temp & 0xFF00) >> 8);

        uint8_t acc = 0;
        for (int i = 0; i < CAN_PKT_LEN; ++i) {
            acc += canPkt[i];
        }
        canPkt[3] = ((uint8_t)(acc)) ^ 0xFF;

        CLI_write("Sending CAN Data %u, %u, %u with checksum %u \n", canPkt[0], canPkt[1], canPkt[2], canPkt[3]);
        retval = CANFD_transmitData(txMsgObjHandle, txMsgObjectParams.msgIdentifier, CANFD_MCANFrameType_FD, CAN_PKT_LEN,
                    canPkt, &errCode);

        if (retval < 0){
        CLI_write("Error: CANFD transmit data failed [Error code %d]\n", errCode);
        }
        //while (gTxDoneFlag == 0);
       //gTxDoneFlag = 0;
    }

I see data over the CLI, however, on my Oscope, I see the MSG_ID, 0101, and then 000000 - which is an Error Message. This repeats a handful of times, then eventually stops.
On the CLI, I see a -3502 code, which corresponds to a CANFD_EINUSE error. At no point do I ever get my 4 data packets that I'm trying to output, and are cloned to CLI.