Thanks. I've been growing vegetable seedlings for years with no issues. Spent a lot of time dialing in the environment, etc. So this is really baffling me. The only thing I can think of is a pathogen in the soil? I got into soil because I wanted to re-use it for environmental reasons, but so far it's a costly experiment! Would love to hear from others that re-use their soil and how they deal with pathogens etc.
Seems to be something 'below the surface'. As you mentioned, my first 3 grows i didn't think about anything they just vigorously grew. No issues. Same methods, etc.