GRow_M8sanswered grow question 5 years ago Hey m8!
At first, seedling looks healthy but if the cup hasn't good drainage (little holes) the roots will have lack of oxygen + the water doesn't evaporates correctly (overwatering) = the plant stops the growth rhythm.
I recommend you to open little holes all over the cup, warmer temps and more carefully watering (better a little dry soil than overwatered)😉