Are you catching a certain edge when you transition to flat?
I noticed I was doing the same thing for a bit and learned to initiate the transition from flat to the turn by leaning hard on my front knee in the direction i wanted to go and a little torsional flex in the same direction. For instance from regular going from flat, I'd push the knee right and push my front toes down, and the board would go and I'd start to press the rear toes in to start digging the edge in to carve.
My issue is doing to too fast and loosing control, either leaning back too much, or not being able to switch back cause I'm turning so sharp. Either way, I hope that helps. After a few runs I stopped doing that.