Mine does a sort of similar thing... Are you dropping them dry and they're catching them, or do you drop them away from the lotls so they get a little soft before they find them? Or do you soak them in a little tank water before dropping them? I've tried all of those to slightly different results.
I'm using Hikari sinking carnivore pellets:
https://www.amazon.com/gp/product/B007QH89AI
I'd guess they're the same size pellets as yours. My lotl is about 4.25 inches now, so I usually break mine in half. With pretty much any food, once it hits the ground he tends to ignore it until I suck it up and drop it again, including pellets, so I've just got to drop them precisely or use soft tweezers.
I used to let the pellets sit in a drop of water to get a little soft before dropping them, but then they were impossible to pick up and he would usually spit them out after two or three chews if he caught them.
When I drop half of a dry pellet, he'll usually suck it right up, and it takes him awhile to chew on it (presumably to make it soft enough). He kinda bloops himself backwards because of the water coming out of his mouth when he chews but doesn't seem to mind terribly. If he's really hungry (like in the morning or right when I get home from work) he's got a much higher chance of not spitting it out. If he's had anything else though, he'll spit it out and stare at the sky hoping I'll drop something better.
This is just a guess... but I think it might be a combination of A) them being a little gummy and harder to get down than a worm or a brine shrimp, and B) all the chomping making them accidentally expel the lightweight pellet, and C) maybe just really liking other foods more. I know mine prefers, in order: Beef heart, brine shrimp, bloodworms, and pellets. Beef and worms are treats though, and he makes a horrid mess of the shrimp so... I try hard to get him to eat some pellets first.
Anyways, those are my guesses. Anyone else have experience with this? Maybe try breaking the pellet in half and seeing if he can get it down without blooping it back out? Also... it seems to be ok, but does anyone advise against feeding them a pellet that hasn't fully gone soft yet? They seem to soften pretty quick, but I worry about it being like an expanding noodle.