While there are several possible reasons that a fat tailed gecko isn't eating, I think the most common reason is that they aren't being kept warm enough. With that in mind- I'm not sure I understand your setup. Is the "basking area" that is 92f out in the open? If so, the gecko may not be using it enough to properly warm up. During the day, this species hides in warm, slightly damp termite mounds. With that in mind, they need a humid hide box that hits 92 on the INSIDE. Use a laser thermometer to confirm, don't go by your thermostat setting. They like small, tight, enclosed hiding spots- not the hollow half logs sold at pet stores. A piece of cork bark they can burrow under is ideal.
Regarding misting twice a day- not necessary, and possibly detrimental. Unless the ambient humidity in your house is extremely low, the humidity in the hide box should be sufficient. If you need more humidity, moisten the substrate periodically. Do not use a full screen top.
Regarding the actual feeding- what is your technique? Are the dubia and mealworms burrowing in to the substrate where the gecko can't find them? You can make a feeding dish out of an opaque deli cup with a lid. Cut a circular hole in the lid large enough to admit the gecko. Are you using tweezers to hand feed it? Not all geckos respond to that- many will shy away. If the gecko is timid, my suggestion would be to dump a few gut loaded, dusted crickets in right at lights out, and let it hunt overnight.
One more bit of advice- do not handle the gecko until it is eating regularly and reliably.
Without knowing more about your set up and your feeding technique, some of my suggestions may be considered guesses. If you can post some more info for clarification, perhaps someone here might be able to offer something additional.