I clone on a commerical level (thousands of clones a week are cycled). Having said that, it looks like your plants are in too low of humidity, transpiring (losing) too much water. I would mist the dome with water, close the vents, and take it out of the light for a few hours.
Heat will cause the plant to transpire faster (think about how you sweat). Your plants have been transpiring too quickly from their looks. We always run in the area of 75 degrees, ambient humidity of around 30-40, and around 80 rh in younger domed clones.
i have seen them in 7 days using a propagator but this is rare normally 11-12 days
7 days is pretty standard for a good aero/bubble cloner , they give the right humidity at the rooting zone without getting them too wet
4 days sounds like bullshit or a very rare freak occurrence