My beardie would not eat any salads with calcium supplement on it.
I would not use any calcium supplement without D3 for beardies. They need it.
Try feeding the insects using forceps. The first 2-3, use without the calcium. This should get him into a food mode where he just starts eating without hesitating. Then feed him the ones powdered in calcium. You don't need to coat them so full of powder, just enough to cover the bug. A baby like yours only needs calcium plus D3 supplement every other day, so you can give him the salad daily without the supplement and only supplement on the insect feeders every other day along with multivitamin (2× a week). Too much calcium is just as bad as too little.
Most importantly are your lights. Make sure you have strong UVB lights, like a Reptisun T5 10.0 (fluorescent) if the fixture is outside the mesh or T8 for inside the tank.