Rotating a cube in multiple directions (forward, back, left, right) not working in a sequence

Getting Started
,
1

Hey!
I have a project with artificial inteligence for my university. The problem basically looks like a 3d grid with some walls a goal and a moveable cube. The cube moves around the grid by rotating in the direction of the movement and moving one space at a time. I want to visualize this i already got the positions done correctly but the rotations are not quite working yet. Each rotation works correctly from the starting position. But when i rotate or move multiple times it gets buggy.

this is the part of the funtion that dose the calculating it is called once when i press an arrow to look at a previous or next state of the solution:

initialRotation = moveableObject.transform.rotation;
initialPosition = moveableObject.transform.localPosition;


MoveDirection LastMoveMade = currentState.LastMoveMade;
if (prevState != null)               
{
    switch (prevState.LastMoveMade)
    {
        case MoveDirection.Forward:
            LastMoveMade = MoveDirection.Back;
            break;
        case MoveDirection.Back:
            LastMoveMade = MoveDirection.Forward;
            break;
        case MoveDirection.Left:
            LastMoveMade = MoveDirection.Right;
            break;
        case MoveDirection.Right:
            LastMoveMade = MoveDirection.Left;
            break;
        default:
            break;
    }
}

switch (LastMoveMade)
{
    case MoveDirection.Forward:
        targetRotation = Quaternion.AngleAxis(90f, Vector3.left) * initialRotation;
        break;
    case MoveDirection.Back:
        targetRotation = Quaternion.AngleAxis(90f, Vector3.right) * initialRotation;
        break;
    case MoveDirection.Left:
        targetRotation = Quaternion.AngleAxis(90f, Vector3.back) * initialRotation;
        break;
    case MoveDirection.Right:
        targetRotation = Quaternion.AngleAxis(90f, Vector3.forward) * initialRotation;
        break;
    default:
        break;
}

elapsedTime = 0f;

the update looks like this:

private void Update()
{
    elapsedTime += Time.deltaTime * animSpeed;


    if (elapsedTime < animDuration)
    {
        float t = elapsedTime / animDuration;
        Quaternion newRotation = Quaternion.Slerp(initialRotation, targetRotation, t);
        Vector3 newPosition = Vector3.Lerp(initialPosition, targetPosition, t);
        moveableObject.transform.rotation = newRotation;
        moveableObject.transform.localPosition = newPosition;
    }
    else
    {
        moveableObject.transform.rotation = targetRotation;
        moveableObject.transform.localPosition = targetPosition;
    }
}