The problem you are having is what I had: low temperatures
I now leave my plants inside by a large south facing window in my office. I'll move them outside in May. They'll go back inside when the over-night frosts return. Usually end of November where I live.
I'm wondering if it's light. They only get about 4-6 hours of direct sunlight a day in that nook (the rest of the day is bright indirect light).
My inside rack has a new problem. I noticed all my cuttings have exploded with shoots and my seeds are starting to sprout (still no Cobra Lily Seed strikes, though) -- and my Purple Pitcher Plant is shriveling up despite having very moist soil.
I have a sinking suspicion I'm going to come home to discover the thermometer with min/max memory I installed in there last night is going to say something horrifying for a max...