Whirlpool dishwasher losing water during wash cycle

We just finished a renovation and can’t get this new dishwasher to work properly. During the wash cycle the water is draining out slowly. Because we have a few cabinets in the way, including a corner cabinet, the plumber hooked up the drain directly to the waste line by going through the floor. He added a high loop of about 18" before it drops through the floor so I can’t believe it’s just gravity pulling the water through.

Anyone ever have a problem like this? What do I do to fix it? I haven’t contacted whirlpool yet in case it’s something simple.

Update: I changed the high loop so it now goes all the way up to the underside of the countertop. This appears to have solved the problem. The instructions did say something to the effect of routing the drain at the counter top or above cabinets, so I guess we’re good to go.