Why line ConsoleKey key = Console.ReadKey().Key deletes oldest "O" on Console screen?

Question

Trying to make snake game. I am using Console.SetCursorPosition(int x, int y) to draw body parts("O"), 2D array to store "O" previous locations and Console.KeyAvailable to detect direction changes. When a key is pressed that is not in the switch statement, drawing stops for one iteration. When a key is pressed that is in the switch statement, Console erases oldest body part.

Debugger doesn't show the reason. Can anyone help me to understand why is that happening?

static void Main(string[] args)
{
    Console.CursorVisible = false;

    while (true)
    {
        ConsoleKey key = Console.ReadKey().Key;
        switch (key)
        {
            case ConsoleKey.RightArrow:
                direction = "RIGHT";
                break;
            case ConsoleKey.LeftArrow:
                direction = "LEFT";
                break;
            case ConsoleKey.DownArrow:
                direction = "DOWN";
                break;
            case ConsoleKey.UpArrow:
                direction = "UP";
                break;
        }

        breakOut = false;

        switch (direction)
        {
            case "RIGHT":
                for (int i = x; i <= 100; i++)
                {
                    Iterator(i, y);
                    x = i;
                    if (breakOut)
                        break;
                };
                break;
            case "LEFT":
                break;
            case "DOWN":
                for (int i = y; i <= 100; i++)
                {
                    Iterator(x, i);
                    y = i;
                    if (breakOut)
                        break;
                }
                break;
            case "UP":
                break;
        }
    }
}

static void Iterator(int x, int y)
{
    Draw(x, y);

    xSlot = x;
    ySlot = y;

    histPoints[slotCounter, (int)place.x] = xSlot;
    histPoints[slotCounter, (int)place.y] = ySlot;

    if (slotCounter >= length)
    {
        Erase(histPoints[slotCounter - length, (int)place.x], histPoints[slotCounter - length, (int)place.y]);
    }

    slotCounter += 1;

    if (Console.KeyAvailable)
    {
        breakOut = true;
        return;
    }

    Sleep();
}