Dishwasher drainage problem
The drain loop is taking the place of a vacuum breaker you'd see on the counter. The loop really has no bearing on how the machine drains. It only stops (hopefully) water from flowing back to the DW from the drain. The pump is obviously working correctly as you mentioned when you checked with a bucket. What you didn't mention or check was whether  the DW was empty of water. In fact unless the water level inside is sloshing around, some residual water will most likely remain simply because the impellers cant force small amounts of liquid out the hose. Some will remain in the sump at the case bottom and then pumped out on the next drain cycle. Your first and only loop should be above the drain where the hose enters the sink drain. Make the top of the loop touch the counter top underside. Unless your DW pump is faulty or damaged it will expel water easily through the loop and down the drain.