I agree with the previous two posters to leave it to the coaches and that it is most likely in the preflight phase. But I will say that I was the type of athlete (and parent) that wants to understand the physics/exactly how something should be done so I'll offer what I think is a very helpful analogy for understanding how to vault properly.
FHS vaulting really comes down to only three things: speed, staying tight and contacting the springboard with the COM behind the feet. What you can show your daughter is that a pencil can do a perfect 10 FHS vault because it is able to do these three things (especially staying tight lol). You can demonstrate this by throwing a pencil with speed at a 45 degree angle with it's "feet" (the eraser) in front of its COM (belly button for person and midpoint of pencil). With the right throw the pencil will flip end over end and do a perfect vault. You can also show that the COM directly over the feet doesn't work (pencil just bounces up and doesn't flip) and that leaning forward would make the pencil just smash it's "face" into the mat (or have to pike if it could bend).
This little demonstration shows that less is often more with vaulting because even a pencil that knows nothing about gymnastics can do it. For a person, it works just like with the pencil. As the gymnast hurdles to the board, if the feet are in front of a vertical chest with tight legs contacting board at a 45 degree angle, the feet will stop (should feel like pushing board forward into table) but the upper body will keep moving forward from the run momentum. At the same time, the board compresses and springs up as the gymnast body gets to 45 degrees on the other side (angle of incidence = angle reflection) which will shoot gymnast up and flip them with no effort. Most of the "heel drive" is really just hitting the board correctly in this manner. And probably 90 percent or more of vault is really just the run and how they hit the board. I never understood why the preflight phase was judged until I realized this.
In your daughters case, I would bet if you watch video of her recent vaults that she is not striking the board with the COM/chest up and behind the feet. She is likely leaning forward and this is causing the rolling. It is counterintuitive to young gymnasts but you want to stay away from the vault mat/table and allow the board to do the work flipping you. But most will be leaning forward instead because that is more natural.