Only thing that has me perplexed is he was eating fine a month ago in the same set up. I thought maybe there was a drop in temps, but it seems the OP has them under control.
I was gonna recommend he be put into a smaller enclosure or more items be added to his current, but was thrown off by him eating fine in there a month ago...
OP, has there been any change to what you are attempting to feed? Anything different you could be doing that you weren't doing before (or doing differently before)?