I am new to the site, and this is my first post/reply, but I wanted to let you know, I have the same issue.
My son got a new beardie for Xmas ( about 5 inches long, young, but not a baby) ( therefore I did too!) and he ate good for a few days, then stopped eating crickets altogether.
We figured it was too much handling during acclimation...No problem left him alone.
Then gave him a
bath, thinking he was dehydrated, and he drank and shed, another non eating cause. No problem figured problem was going to be solved.
Still no crickets, some mealworms, and waxworms, hates phoenixworms.
For some reason, I am stressing about him, sine he just chills under his hide, comes out to sun occasionally, but not active like everyone says they should be.
Temps are good ( 75-80 in cool, 95-100 on hide, on floor ( with under heating pad) under light about 109), so Im good with that.
He seems healthy, but just mellow. Not skinny, not unhealthy, but don't want to make a mistake.
Ill let you know if I have any luck, but I thought he was too young to officially brumate, so maybe he is just "sort of" brumating...not sure.
This dragon gets more care than my kids, with his chopped salads, trips to stores for all sorts of special worms, etc. Not complaining, just laughing at myself.
Good luck and let me know if you have any luck.