Do you have any warning lights on the dash? Any Diagnostic Trouble Codes DTCs?
If it is like earlier models, there is an actuator motor with dual windings, dual angle sensors (hall sensors), and an encoder. The controller is a so-called smart box with position learning for the Park position, and a multitude of DTCs and diagnostics tests in the FSM.
Without DTCs available, the first thing would be to check for corrosion or looseness in all the connectors, and check the wiring (rodent damage).
If you are a diy sort of guy then you might remove the mounting bolts for the actuator to lift it off of the splined shaft to access the manual rod, and rotate it by hand to see if there is any CCW travel available to back it off further. The Park position (locked) is learned by noting the encoder when the motor stalls; and then for Driving back it off nnn encoder counts to the unlocked position. Maybe the encoder is dropping counts and not backing out of the way far enough. An oscilloscope would help in troubleshooting to monitor the encoder.
Don't know if the encoder is a separately replaceable item, but is the most likely culprit after connectors and wiring (i've had to replace many encoders in CNC and machine tool applications).
The FSM "repair" is to replace the gearbox if there is an actuator fault. Good luck and let us know what you find.