Clones usually yellow a bit and look more sickly right after their first transplant. Don't worry about it unless the top leaves start showing signs of problems (the lower leaves will probably become yellow and crinkle, this is the plant naturally drawing nutrients from those leaves to provide for new growth). If you see new growth sprouting up, don't worry. Oh, and never let light touch the roots, it will damage them.
Clones should be done in rock wool before being put into the pots, You want to cover them to keep in moisture and heat you should also use a clone stimulator like Olivias Stimulator never fertilize your clones. Your plant look to be burnt with fertilizer even a little fertilizers will burn them.
I have no experience using clay pellets, they may act different.
I transplant cubes into mulch, or Canna Coco and I find that there is usually ONE in a tray of 18 that does that. Sometimes they snap out of it - sometimes they don't. (Usually they do). Since I am doing volume I don't stress over the one that doesn't want to live- I just reuse the pot.
If I'm cloning for MY use, I always start 2x the number that I want to use - then cull the weaker out. There is an old Yiddish saying that goes something like this: "As it begins, is how it ends." If a clone starts out badly - it is one that I don't want. I do not want a challenge, I don't want to fight to keep a plant alive till harvest.
I think it will prolly snap out of it. I bet it already has.