[launchd-dev] LaunchAgent suddenly appears in Dock bouncing when CGImageSourceCopyPropertiesAtIndex is called

Hi all, I've got a launch agent working and communicating with it using a terminal command nicely. I'm using NSXPCConnection classes. If I call CGImageSourceCopyPropertiesAtIndex within the launchagent then the launchagent appears in the dock bouncing. Calling CGImageSourceCopyProperties doesn't cause the same issue. I have tried adding to the LaunchAgent's bundle plist the key LSUIElement with a value of YES. This doesn't change the behaviour. The LaunchAgent continues to work properly and the dictionary obtained from calling CGImageSourceCopyPropertiesAtIndex is saved to disk which is what I wanted to happen. I'm linking against frameworks Foundation and ImageIO. Any thoughts as to why? Kevin