Are you conveying this turn around into the saddle? I ask this because it could work two ways for you. If your using this for turn around a under saddle, then I wouldn't have her suck back too much, for some horses, and I say 'some', sucking back into the spin works, but for others it create more issues. But a turn around is supposed to be a forward movement.
Have you thought about circling her tight around you on the lead, ie. Jogging her and bringing her down into the turn, this would require you to pull her in tighter to you and keep the momentum going and you would be moving a lot faster around beside her shoulder and you would be on the inside of the turn instead of the outside.....it's worth a try, you might be suprised........OR when that hip moves push her out into a tight jog around you going in the direction you were asking her to turn and make her move that hip A LOT then bring her back down into the turn around....she will want to keep that hip still after you've pushed her out and made her work it each time she swings it out in the turn around.....haha a bit of reining psychology there!!