m0useanswered grow question 1y ago Could just be the seed, if the others are doing well and this one is not it might just be its own thing. Not all seeds are 100% and not all plants from seeds are great, I'm sure it will bounce back and do fine. Temps could be increased a bit. 22-24c day time vs 20c. 18c at night is fine as long as its not doping to much past that. Remember to mist the top portion of the medium to prevent it from drying out to fast.
There is a lot of perlite in your medium I would not expect overwatering to be a issue, but if it is, less is more till it can build a stronger root base, keep the medium moist but not soaking wet.
Good Luck!