After dragging and dropping a pin, pin becomes unselectable

Using an MKMapView I have written some code that allows a user to drop a pin after a long press and then have the ability to drag the pin to a new location after using a long press on the required pin. When tapping (selecting) a pin it should segue to a new view controller.

After dragging and dropping a pin the pin becomes unselectable until a different pin is tapped or the map is dragged around a bit.

the code can be found at https://github.com/Cal-um/Virtual-Tourist-iOS-NanoDegree-P4/blob/networkingBranch/Virtual%20Tourist%20iOS%20NanoDegree%20P4/SelectLocationWIthPinViewController.swift

Any ideas what the solution to this problem is?