What caused this to happen to my plant?

I recently took a newly rooted rapid rooter clone and transported it to a single 5 gallon bucket DWC and this is what happened (see photo). I did this with 4 plants total and the other 3 came looking well. Not even 24 hours later, this is what I came home to. I have an air stone is each bucket, water levels all the same in all buckets, water temp is fine in all buckets, my question is, why did this one turn out this way?

I think it needs humidity, looks dry, a bit thirsty.. But again i might be wrong.

were there any roots shooting out the bottom of the net pot?

Few things. If these were in a dome you have to slowly acclimate them to out of the dome humidity, a hardening off if you will. make sure the water is hitting the roots if its an air stone type thing make sure its splashing the roots and the hydroton. IS the water at ph 5.5-5.8 max? Lights not to close or strong first couple days. Whats the humidity around the plants?

Humidity is always around 25-40%. There were no roots shooting out through the bottom of the netpot (none of them were when i planted them however). They were not in a dome, they had been sitting in a rapid rooter tray underneath a t5 light right before I put them under HPS lights. PH is around 5.8-6.0 at all times. Lights are nowhere near the plants, probably a good 2 feet away. Like I said, I planted 4 of them, 3 of them still look perfect, and this lone one turned out like this, I just don't know why...

You probably ripped the roots out of the stalk when you transplanted it. Hold the plant and pour out the hydroton and look at the roots. You need to put the bottom of the stalk on the bottom of the net pot and hold it there and then put hydroton on it. The roots should travel outside of the bucket within 2 days or something is probably wrong.

Id drop the ph closer to 5.8. Yeah roots should be big enough to be hanging out the pots in 24 to 48 hours if not they can die easy with no water to take in which is how this one looks.