ah, I've had the same thing, both with my bearded dragon and with my fire bellied toadlets.
For my fire bellied toadlets, I am switching from pinhead crickets to wingless fruitflies. I'm hoping that will be easier for them to eat, hopefully that will help. I'll let you know...
For my dragon, she has a really hard time getting fruits and veggies into her mouth.One thing that helps is if I hand feed her- I hold the food above her and as she goes to bite I just sort of drop it into her mouth, and this works well... not sure how hand feeding a pixie would go- maybe suspend the prey item with tweezers in the air above her, and see if she bites?
One thing I do for my dragon when she's really having a hard time is put a little bit of honey on the back of the prey, helps it stick.
But for your pixie, maybe try hand feeding, or try wingless fruitflies, I've been told they're the best for helping out critters in catching their prey, cause they're so fool proof.