When I start a load, the water runs but the tub never fills up. I once started a load and left for hours and came back and the water was still running but the tub still had not filled up. Not sure how this is possible as the drain is about the same height as the top of the tub. When attempting to fill, there is no sounds other than the water running, it doesn't sound like the pump is running. What is going on?

Thanks