Hey Steffen,
I hope you are staying safe during these difficult times. I have a customer that is using a D230 and everything works fine but when we try to retrieve a park (*31 on our Freeswitch Platform) it never attempts to retrieve the call. I have tried deleting all the feature codes on the web interface of the phone.
The phone is manually provisioned and on the newest firmware. Is there anything you could think of that might stop the phone from attempting to retrieve a parked call.
Take care,
Matt