I saw a problem long ago on an American model car that had the steering interlock along with a Park interlock when the key was out of the ignition. The car was parked on a slope in such a way that the front wheels were turned, so that they applied a lot of pressure against the steering wheel.
In turn, this pressure was placed against the steering lock, which was directly tied into the steering column Park lock.
Easily solved by applying turning pressure to the steering wheel to release the pressure against the steering/Park interlocks.
So, try moving the steering wheel a bit.