IMO- I think they got stressed from the transplanting.
I've used M3 soil before it's good stuff. just add water.
They look over watered, but stressed plant will look like that also.
Your soil isn't to wet right?
Humidity is a little low, but that shouldn't be do much of a problem.
Did you have the clones under a Humidity dome? That might stress them going from High humidity to low humidity.
"Super Thrive" will help a stressed plant. there are other that will do the same job.
They should bounce back for you and start perking up.
Good Luck on Your Grow.