Because on auto, it will lock as soon as you apply throttle or brake. Throwing it into a corner like that is locking your dccd.

I found manual full open is best for slides.

The auto is not suitable for tight corners where you want to encourage loss of traction.

The other option is to leave on auto full lock, then select your gear, turn in, moderate throttle, pull your handbrake to bring out the back, release and maintain throttle