Need to pull the DW out and pull drain hose off of bottom of tub and see if there is any blockage there, or the drain hose going to your sink drain, and @ the sink drain also.

Most likely you have some blockage since you can hear the "pump" draining.

Worst case scenario, pump is bad. But check all hose fittings for blockage.

Also, when you actually remove the drain hose that goes to your sink @ the pump, you will see a red piece of rubber mounted in the pump. This serves as a "check Valve". Make sure it's not stuck in the pump. Move it back and forth with your fingers to make sure it's opening and closing.