looks like the nutes in the mg soil is alittle to much for there young age.Next time fill your cups up with a soil with no nutes. Or bottom half mg. top half with no nutes. Also can start in peat pellets then place into mg soil after a week or when ever roots penatrate bottom I alway cut the netting on the bottom of the peat pellet after it swells, But before putiing seeds in. This assures the roots will pass with ease..