Hi.

Open the air gap, check for clogs, remove the drain hose from air gap and see if there any debris.

If you can't find any restrictions in the drain remove the toe panel and with control set for drain see if the drain pump is running.

Using the multimeter check for 120v at the pump contacts.

If you are getting 120v and the pump is not working or it's working, but not draining properly - replace the pump.

The drain pump Part number: AP4019644