My first Pacman frog...

[lumpbump]

Hello & Welcome to the forum!
There could be a few factors......it may be that he is intimidated by the large enclosure. It may simply be re-location stress. As for the burrowing, that is normal, they are ambush predators and this is how they prepare in case food comes along. Have you tried feeding earthworms/nightcrawlers? Cut appropriate sized bits off the worm and try tong feeding.
Pictures of the frog & enclosure would help us give some advice.

No I have not fed worms. I have seen your tong feeding 102 video. I dangle the roach like you do the worm bits for up two to three minutes and wiggle it too. Here's some pics .