Is my dishwasher air gap manufactured incorrectly?
I'm going out on a limb here, but it is probably more indicative of the solution.

You have a question outstanding that no-one answered yet, and then you posted this one, which ironically is going to draw questions that feed right into your other question. So for sake of completeness, you may want to merge them since both of these questions DEFINITELY feed each other, and mark the other dupe or link it to this one.

Question.... in question:
Can dishwasher tubes do 360 loops?

There is no "pressure" from your air gap from your dishwasher, so the air gap is almost certainly filling up until the loop you have created BELOW the disposal is filled and there is (if ever) enough water weight to move water into the disposals drain.

Also, make sure the disposal &amp; its drain is clean &amp; clear.

The dishwasher &amp; disposal install kits instructions should talk about this. Here is an example from a google search:
http://structuretech1.com/dishwasher-drain/

From the two posts, I would shorten the disposal line and run it directly.