It could be the greenhouse environment is too hot or there is too much light. Our Goodyera species (MN) are all forest dwellers so we’ve found that they do better under shade cloth and are pretty happy in a shaded hoophouse outside or in a cooler greenhouse.

We’ve also been playing around with exposure to light in the seedlings much earlier than typical (like right around when we move them from mother flask to replate), and potentially letting them be exposed to light in flasks for a while before potting up.

I’m only beginning to have success growing terrestrial orchids in vitro, and haven’t grown Goodyera specifically. Have you tried giving the young seedlings a dormancy period in the refrigerator (either still in their vessels, or rinsed off and in damp sphagnum) before transplanting them out in the spring? I have found that the shock of taking the seedlings out of their vessels causes them to “want” to go dormant. Instead of fighting this and trying to get them to grow right away, you may have more success with acclimatization after providing a dormancy period.