humidity. cutting at that stage needs lot of humidity. not enough root to support the top and they are out in the open, although in the bathroom. so, they look fine one day, and when you look at it next day, the leaves are drooping.. soon they will drop.. and soon the cutting will dry out and die. once you see that much top growth on the cutting, you will have to check for the roots daily and make sure the top gets lot of humidity. humidity bin works great for this. once root is well established, then you can leave them out longer, but still cuttings indoor during winter.. it's a balance thing.
i'll leave top off my humdity bin maybe 15 min at first.. then increase the time till they can stand 2 hrs. if there is any sign that leaves are starting to droop, the top goes back on. check for mold daily.