Looks as though my one seedling Tiamat has some nutrient burn from the Happy Frog soil. I originally thought it may have gotten too much water being the smallest of the three planted seeds but now as it is getting larger that doesn't seem to be the case.
Having them in a controlled atmosphere tent there is no longer a need for the humidity domes. Hopefully Tiamat regains its color and whatever is happening works itself out after they have all had some time to grow.