I have read that it's usually recommended to feed cats at least three times a day, especially when you're dealing with younger kittens. I gave two daily feedings a try, and had problems with my older cat vomiting (which happens because the cat's highly acidic stomach can get upset when it goes too long with out food). That doesn't mean you have to rush home during your lunch hour to feed your cats three times a day - I feed mine in the morning around 8am, then again in the evening around 5-6pm (or as soon as you get home from work), and one last time right before I go to bed. I think that 12 hours is really a long time for a kitten to be going with out any food.
I also had problems getting my older cat to actually chew her raw, and not just lick all the wet food around it. There were a few things I did to help her get used to chewing her food. First thing was to switch her from pate style canned food to chunks in gravy (I used Weruva, Wellness pouches, and Tikicat canned food because that's what Sassy would eat). Having her eat chunky food got her used to the idea that she was going to have to chew at every meal. At first she wasn't thrilled with all this extra work, but she got used to it
Plus when it came to mixing raw in she HAD to chew, so she wasn't just licking all the wet and leaving all the raw. I tried mixing with pate food for a long time, but switching to chunky food was what actually got some of the raw in her. So I just thought I'd mention it.
When I finally started giving her full raw meals I was stilling giving her canned in the morning. Then in the evening, after she'd gone without food all day so she was nice and hungry, she'd get a meal of JUST raw meat. The first week I did this I actually used a fine cheese grater to turn the raw meat into textured mush. It helped - as did crumbling Temptations over said mush, or dribbling a little tuna juice over it. After about a week of that I was sick of the hassle, so I used kitchen scissors to cut her meat up. It took a long time to get her eating bigger and bigger pieces, but I just kept slowly increasing the size and kept the bribes handy. She still has trouble with bones, so those are cut up a lot smaller - but she's slowly getting better at it. Last bone-in meal there was definitely some actual crunching going on.
And, like you, I had no problems what so ever with transitioning my younger cat. While I was trying to feed Sassy itty bitty pieces of raw beef heart from my fingers, Moxie jumped up on the counter and devoured a huge chunk straight off my cutting board. The first time I offered them a chicken wing each Sassy looked at me like I'd lost my mind, while Moxie had eaten the whole thing in about 30 seconds.
Just keep trying different things, and hopefully Lucky will soon get the idea. But really, I think you should probably add another meal in there, for your younger cat especially. Kittens need a lot more food than adults. I'm not sure exactly how much (me, I'd be inclined to just let him eat until full), but hopefully someone else on here with more experience can help you there. Good luck!