What's your growing environment like? Humid? Did you keep the soil mix moist?

Not humid. Yes, I've kept it moist. Dryness is not the issue.

Growing in Miracle Gro Organic Choice potting mix which is not good for containers as it turns out. Way too heavy. Maybe that is an issue. But tbey don't seem bothered until the true leaf grows for whatever reason.

Could it be damping off? Since you haven't given a photo that is my guess.

I used the same potting mix before but found it infested with aphid eggs. I actually started some alpine strawberry seeds in them in January and had to kill a load of aphids by hand a month later. The strawberries did well though once the infestation is under control and I just planted them out in the garden. So I am tempted to say the soil texture isn't your problem.

I don't know. I don't think so. I grew some tobacco sprouts right along with them and they have been fine. Not a single one has died.

As it turns out, it was the potting mix. I am having 100% success with a different mix. Another is also experiencing 100% death rate from the same problem.