MSP430F6779A: I2C not working properly

So, I have been trying to receive some digital inpits bits connected to the I/O expander using I2C. The code worked once few months ago, but now when I am trying again it isn't working. When I added a breakpoint in my interrupt vector table for NACK interrupt flag, I found the microcntroller is getting a NACK flag. I am 100% sure that the slave address is correct (0x19). I have enabled all the interrupts, but the code get stuck in a while loop when I try to recieve byte information. This shows that the connection between the master and slave is not established and it is causing the problem. I have tried everything to make it work, but it isn't working. Please help me out here. 

The part where I am getting stuck is below. When I try to recieve the byte in the mains while loop, the code get stuck in the EUSCI_B_I2C_masterReceiveSingle while loop. When I try to call the same function in the interrupt as shown in the code below, the controller doesn't reach that statement because RXIFG bit is not set.  

uint8_t EUSCI_B_I2C_masterReceiveSingle(uint16_t baseAddress)
{
    //Polling RXIFG0 if RXIE is not enabled
    if(!(HWREG16(baseAddress + OFS_UCBxIE) & UCRXIE0))
    {
        while(!(HWREG16(baseAddress + OFS_UCBxIFG) & UCRXIFG0))           // the code get stuck here 
        {
            ;
        }
    }

    //Read a byte.
    return (HWREG16(baseAddress + OFS_UCBxRXBUF));
}


This is my whole code for receiving data through I2C

#define SLAVE_ADDRESS 0x19
#include "driverlib.h"
uint8_t RXData;
void main(void)
{
    //Stop WDT
    WDT_A_hold(WDT_A_BASE);

    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P4,
        GPIO_PIN4 + GPIO_PIN5
        );

    EUSCI_B_I2C_initMasterParam param = {0};
    param.selectClockSource = EUSCI_B_I2C_CLOCKSOURCE_SMCLK;            //Setting clock source to SMCLK
    param.i2cClk = UCS_getSMCLK();                                  
    param.dataRate = EUSCI_B_I2C_SET_DATA_RATE_100KBPS;                 
    param.byteCounterThreshold = 1;                                     //Number of bytes to receive 
    param.autoSTOPGeneration =
        EUSCI_B_I2C_NO_AUTO_STOP;                                        //No auto stop. I can set it to stop if the desired bytes ( in this case - 1) is received. 
    EUSCI_B_I2C_initMaster(EUSCI_B1_BASE, &param);

   EUSCI_B_I2C_setSlaveAddress(EUSCI_B1_BASE,
                                SLAVE_ADDRESS
                                );

    //Set Master in receive mode
    EUSCI_B_I2C_setMode(EUSCI_B1_BASE,
                        EUSCI_B_I2C_RECEIVE_MODE
                        );

    UCB1IE = 0; 
    //Enable I2C Module to start operations
     EUSCI_B_I2C_enable(EUSCI_B1_BASE);

     EUSCI_B_I2C_clearInterrupt(EUSCI_B1_BASE,
     EUSCI_B_I2C_RECEIVE_INTERRUPT1 + 
     EUSCI_B_I2C_BYTE_COUNTER_INTERRUPT + EUSCI_B_I2C_NAK_INTERRUPT);              //Clearing all required interrupts 

 
    EUSCI_B_I2C_enableInterrupt(EUSCI_B1_BASE,
                                EUSCI_B_I2C_RECEIVE_INTERRUPT1 +
                               EUSCI_B_I2C_BYTE_COUNTER_INTERRUPT + EUSCI_B_I2C_NAK_INTERRUPT
                               );
    
    
   __enable_interrupt();
   //__bis_SR_register(GIE); 
    while(1)
    {
        __delay_cycles(2000);
        while(EUSCI_B_I2C_SENDING_STOP ==
              EUSCI_B_I2C_masterIsStopSent(EUSCI_B1_BASE))
        {
            ;
        }
        // I2C start condition
        EUSCI_B_I2C_masterReceiveStart(EUSCI_B1_BASE);
     } 
} 

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_B1_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(USCI_B1_VECTOR)))
#endif
void USCIB1_ISR(void)
{
    static uint8_t count = 0;
    switch(__even_in_range(UCB1IV,0x1E))
    {
    case 0x00: 
      break;       // Vector 0: No interrupts break;
    case 0x02: break;       // Vector 2: ALIFG break;
    case 0x04:
        EUSCI_B_I2C_masterReceiveStart(EUSCI_B1_BASE);              
        break;           // Vector 4: NACKIFG break;
    case 0x06: break;       // Vector 6: STT IFG break;
    case 0x08: break;       // Vector 8: STPIFG break;
    case 0x0a: break;       // Vector 10: RXIFG3 break;
    case 0x0c: break;       // Vector 14: TXIFG3 break;
    case 0x0e: break;       // Vector 16: RXIFG2 break;
    case 0x10: break;       // Vector 18: TXIFG2 break;
    case 0x12: 
      RXData = EUSCI_B_I2C_masterReceiveSingle(
            EUSCI_B1_BASE 
            );                                                               
      break;       // Vector 20: RXIFG1 break;
    case 0x14: break;       // Vector 22: TXIFG1 break;
    case 0x16:
        RXData = EUSCI_B_I2C_masterReceiveSingle(
            EUSCI_B1_BASE
            );                                                               // Get RX data

        break;           // Vector 24: RXIFG0 break;
    case 0x18: break;       // Vector 26: TXIFG0 break;
    case 0x1a:
        break;           // Vector 28: BCNTIFG break;
    case 0x1c: break;       // Vector 30: clock low timeout break;
    case 0x1e: break;       // Vector 32: 9th bit break;
    default: break;
    }
}

Please help me, I am ot sure what I am doing worng. I have spent weeks now trying to figure this out.Pls help. Thanks