I don't know if it is the same problem that i got. But in my case there was trouble with heat stress. it was too hot and too dry in closet. it was about 30 degree C and 30% air humidity. since it dropped to 25 degrees and went to 45% they started to grow pretty well. I also mixed a little bit of H2O2 to water. I was told it will help the roots to recover and to get more oxygen. seems it helped, but i am growing in soil.