Ing tumbler

Yes there is a spring loaded pin of sorts that popes out into a hole at the rear of the cylinder’s housing when the cylinder is properly seated. It has to be depressed while turning the key to free the cylinder so it can be removed. That spring may be broken or missing causing the pin not to move, or there is enough crud built up at the base of the housing to disallow the cylinder enough travel to full stop to enable the little locking pin to enter its hole in the housing.

As others have stated, remove the ignition switch from the dash to give it a good look over. The problem will be easy to spot, and correct.