Watered twice daily or lightly misted twice daily? When I first started, I killed so many seedlings by overwatering them. Let the medium dry out a bit, then water with a tablespoon, or just mist the top of the soil. Could be your miracle grow, but more likely, your seedlings are damping off.
Also, your light wattage & height?
Fill out this support ticket to give the experts (not me!) a better idea about what’s happening.
Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so = NA
Strain; Type, Bag seed, or NA
Soil in pots, Hydroponic, or Coco?
PH of runoff or solution in reservoir?
What is strength of nutrient mix? EC, or TDS
Indoor or Outdoor
Light system, size?
Temps; Day, Night
Humidity; Day, Night
Ventilation system; Yes, No, Size
AC, Humidifier, De-humidifier,
Co2; Yes, No
Add anything else you feel would help us give you a most informed answer. Feel free to elaborate, but short, to the point questions and facts will help us help you.
If you post pics, people can give better advice.