Volatile Keyword and Array Thread Safety

In the provided code, the data array reference is declared with the volatile keyword. What potential concurrency issue still exists when multiple threads execute the updateElement method?

public class VolatileArray {
    private volatile int[] data = {0, 0, 0, 0};
    
    public void updateElement(int index, int value) {
        data[index] = value;
    }
    
    public static void main(String[] args) {
        VolatileArray va = new VolatileArray();
        Runnable r = () -> {
            for (int i = 0; i < va.data.length; i++) {
                va.updateElement(i, i + 1);
            }
        };
        Thread t1 = new Thread(r);
        Thread t2 = new Thread(r);
        t1.start();
        t2.start();
    }
}