Villagers from villager breeder disappearing in trading hall, villagers brought from regular villages are fine

This is my villager trading hall, and all is normal except these two spots should have villagers, but they keep despawning every time I bring them here. I break the minecart when they're fully grown and I start trading. But after 30 or so minutes, they despawn, which isn't something villagers do. Even if my trading hall is not as organized, that shouldn't matter as trading halls don't need to be as consistent as villager breeders do, which I copied 100% correctly from a youtube tutorial and it works perfectly fine. Villagers despawning is not a problem from the breeder itself. I even named one of the villagers, and yet both still despawned.
Lastly, it's not a suffocation issue either, because every other villager is set up as you see here, and they never despawn nor suffocate. It's incredibly frustrating.