nigel

have a flat white rather than foil surface; which reflects light and heat irregular.

given the condensation i think too wet?

but then i see root zone exposed to air and think too dry?

So maybe too wet around stem, and grow pot stuff needs protection.

More stronger light will just make it worse. you need to upsize your box and create a gently lit, stable environment, even temps and get them growing first.

Never used grow blocks, but would be planting them in bigger pots so roots have somewhere to grow, provide a bit of support, and are protected from drying out.

Water around the potted up plant not on stem, this encourages roots to go out beyond medium they are in, into pot soil. good luck nigel

__________________
"There are no problems; there are only solutions." Bill Mollinson