Sounds interesting. Do you have an explanation? Or is it simply due to a more trained core muscle system?
I don't know if I can answer this as completely as you would like, but I do know it doesn't have anything to do with a "more trained core muscle system." Both styles of turns (we'll call them "ballet" and "latin" for clarity sake) require a lot of trained and toned core muscles.
The difference comes from the rotation of the body. In ballet turns, everything (the ribcage, shoulders, spine, hips, etc) moves together. In latin turns, the turn itself comes from the twist of the spine - the ribcage moves first, the hips and head and feet follow. There is a very clear, distinct separation between different parts of the body which does not happen in ballet. That's about the best I can break it down - but I know the experts here can do a better job.
As for the OP, I know I had problems falling out of turns for a long time (still occasionally do). It usually is one of or a combination of any of the following: tilting in the middle of the turn, dropping a shoulder, holding back a shoulder, collapsing the core, arching the back, tilting or otherwise moving the head off the center of the body, not getting over the feet...the list is endless, and without a lot of point-by-point breakdown and a visual, it's hard to tell what it might be. Also, in my case, it least, the cause changed from day-to-day, but the result was oddly always the same...good luck!