Q.Greenhouse Seedlings Dying Inch Above Potting Soil
I am having a problem with my seedlings (in my greenhouse) dying. They are all starting to shrivel at the stem about an inch above the newly repotted soil. I transferred them into larger pots until I can transplant them into the garden. They were very healthy seedlings, but about one week after transplanting into the new pots, the stems just shrivelled up.

Certified GKH Gardening Expert
It sounds like they are damping off. This article will help you with that:
https://www.gardeningknowhow.com/garden-how-to/seeds/what-is-damping-off.htm