I think you're overwatering them. I've lost a seedling to dumping off once that paused and started to wilt little by little. Keep an eye on your water practices, only give them when you put your finger in the first inches of soil and it comes out dry. Also check RH.
If it is dumping off I'm afraid there's not much you can do...but it's only over when it's over, stop watering and give her light.