Kerbal Space Program

When docking and undocking to other ships and debris, sometimes the undocking direction gets flipped around and the port fails to undock in the future. Here's a diagram of the active vessel currently experiencing this (see attached image and persistence.sfs files).

• See attached persistence.sfs. First vessel contains problematic docking ports.
• See error message in unity log file. Procedure was: start game, fly to first vessel "Sisters of EVE Academy", try to undock one of the two stuck docking ports, and leave game.

Noteworthy log entries:

When switching to the station with the docking problems, the vessel is referred to as dockingPort2:

[dockingPort2 (Sisters of EVE Academy)]: Orbit started

When rightclicking on one of two problematic docking ports and trying to undock this error is thrown:

Unpacking Sisters of EVE Academy

(Filename: /BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/LinuxStandalonePlayer/UnityEngineDebug.cpp Line: 54)

NullReferenceException: Object reference not set to an instance of an object
  at ModuleDockingNode.Undock () [0x00000] in <filename unknown>:0
  at ModuleDockingNode.Undock () [0x00000] in <filename unknown>:0
  at BaseEvent.Invoke () [0x00000] in <filename unknown>:0
  at UIPartActionModuleButton.OnClick () [0x00000] in <filename unknown>:0

(Filename:  Line: 4294967295)

Game Paused!

Background:

• Bug occurring with different size ports: http://forum.kerbalspaceprogram.com/showthread.php/31591-Clamp-O-Tron-Sr-won-t-undock
• Another Kadet provides a persistence file. Also, Grom describes a procedure to quickly reproduce bug: http://forum.kerbalspaceprogram.com/showthread.php/28084-NoFix-Unable-to-undock
• Several reports with persistence files: http://forum.kerbalspaceprogram.com/showthread.php/25419-Open-Can-t-undock
• Not sure if related: http://forum.kerbalspaceprogram.com/showthread.php/28438-0-19-1-Docking-ports-set-to-disabled-after-connecting-Save-file-included