it might be because it's not wiggling enough. Diggy ignores night crawler until I wiggle them with tong n than he's hooked ever since. (or maybe it's the shinny tong? cuz he went after it a few times when i try to pick up his poop lol)
I usually feed him before I go to bed. main light went off around 8pm kind gives him a few hr to wake up. 1 large night crawler plus 4~5 dusted crickets, which i left them running around the tank for him to play around over night. adult female crickets have to be tong feed to him other wise u gonna have a ton of ping head running around before u know.
once a while i'll leave a medium/large guppy in his water dish, if they are still there the next day than feed it to him instead of the night crawler, cuz guppies dont last that long in there. poke it a little and make it bounce around if it's just laying on the floor.
btw i tried out the turtle/fish food mix too. just another method i found online where they wet the turtle food+vitamin+calcium (whatever the frog needs)and mush them together into a little ball, then tong feed the frog. It cost a lot more but I figure it's a good way for Diggy to get his missing nutrition, so I decided to do it once a week. basically if i move it in front of him enough(n touches his mouth a little) he will go for it. the only thing i dont like about this way is that my finger stink with shrimp smell from the turtle food...