I suspect a hidden JP in a previously surveyed system. Is there a way to reset a system's survey status in C# so I can find the bugger?
You probably have to use spacemaster. Unsurvey the system then survey it again.
PS: Some people to be more realistic unsurvey the system and then send ships in again, some others just handle it from Spacemaster fully (would be on the cheating side? depending on you)