Were the clones hardened off when you bought them? If they weren't, and hadn't yet developed many roots, you might consider getting them under a makeshift humidity dome for a little bit longer. They look to me like they're drying out and not taking in much moisture through the roots. I'd also back the light off a bit more, since unrooted clones really don't need intense light... just enough to establish a good root system. And also be sure that you don't let the rockwool cubes dry out entirely, which can happen quickly under a MH. That's often a death sentence for new clones.