Be patient. Try putting in a bowl/cup with crickets. Crickets should provide enough movement to get the small dubia's moving to. Trigging a feeding response.
I found a cloudless giant sulphur (Phoebis sennae) resting on a corn stalk this morning. So this girl had some butter fly with her breakfast of roaches, worms, and crickets.
Try removing the gel. If the crickets are get their moisture from the gel, they have no need to eat the greens. Thristy crickets will mow through carrots and kale to get to the moisture inside the root and leaves.
Is there any stray insects in with him. Spider, superworm/beatle, earwig, roach? or even big hungry cricket. I would remove everything from the cage to check for anything that might of fed on the chameleon. It looks like something might have snack on him overnight.