If your ph and all other conditions are good, i would say the light power is to low. But #1 is doing great so i dont think so. By the way you could go closer with the light and test it (you got nothing really to lose 😅 but keep the distance to #1 because she is doing good)
Ps: Check the ph of your outcoming drain, it looks like she got little nutrients lock out. (Deep green leafs from week 9 and it would explain the brown dots which looks like cal/mg deficit)