i know this sounds rediculous but when my dragons first came home i had a sililar prob. I threw a duvet cover over the viv to give them ultimate privacy and i started to hear little muchies. I found once mine got over the initial shock of eating in a different home it was clear sailing and now i cant slow them down, they both eat for England. I dont know if this is the case with your beardie but it worked for me and definatly worth a try.
Bearded Dragons: Arora, Saphira and Ember and Platnum.