I'll venture to guess that your problem is clones. (You said you've done this before, then mention doing clones for the first time). Clones aren't the same as seeds. My clones, while still in rock wool cubes are able to handle half strength veg nutes just as soon as roots show, slowly transitioning to full strength veg nutes (.9EC) within a week. Seed plants might go two weeks without any food needed. So, my guess is that they were starving. Don't they look that way to you in the "before" pics? They certainly didn't have "no problems at all." They should look like pretty, green little plants.
My advice: Toss 'em and start over. And feed clones like they're hungry from the beginning. As soon as clones are subjected to strong light, they need food.