So I have the same issue except the garbage disposal plug isn't the problem. My unit drains fine but when I go to start a new cycle, the wastewater pump kicks on for a few seconds then the water inlet kicks on for a few seconds then the wastewater pump again and then I get the E24 code. This cycling happens during the first minute of the cycle, consistently. I just took the toe panel off to observe and accidentally opened the door during this short cycle and then closed it again. This time though, the wash cycle actually ran completely and didn't give an error.
I've also noticed that if I disconnect the drain line from the garbage disposal and suck out the water remaining in the hose after the cycle runs, it will start and run just fine without having to open the door.