Thanks for the question.
Check the front, inside, lower corners of the dishwasher tub for black corner gaskets, one on each side. Are they missing or damaged? In either case, the corner gaskets will need to be purchased and are available at Camco Parts stores
Also check the drain under the sink for a blockage that could cause the problem.
Thanks for your answer, but it seems non-applicable at the moment. The Black corner gaskets are in place and seem to be not cracked or leaking. You should also know that our dishwasher in not built-in beside the sink, but has a hose going down through the floor into the basement. It is difficult to access because we built the dishwasher into a standalone steel frame with a piece of wooden "counter" sheet on top. It could be that the drain hose is clogged at some point with food particles or the like. Could this explain why the water came up too high in the dishwasher early in the cycle? (it's possible it was on a second rinse though.) I can understand why this would cause it not to drain at the end of the first cycle.
Yes if its draining through the floor it could be a clog and not completely draining the water.
disconnect the drain under the floor and see if its draining out full force if its not the problem could be a kink in the hose.
I looked under the dishwasher and could not see any serious kink, though it seemed to be a little flattened, but not totally.
I checked the hose in the basement, which connects to the sewer line, and we advanced the dial on the washer, which caused it to discharge full force, which makes me wonder if there ever was an obstruction there.
Well now that you disconnected the drain try another load to see if it cleared when you disconnected the drain the flat spot is one place to look thats all it takes to cause a drain problem.