2000 Buick ignition key stuck

2000 Buick regal ignition key will not turn to lock position when turning off car.
by turning steering wheel back and forth several times it then turns to off position and key can be removed. What can cause this?

my car would act up at times like you describe and it turned out to be the shifter assy. the dealership repalce it under warranty. when it does it move the shifter out of park and put it back in hard and see if it will turn off.