Having played since the beta I can say this bug was not always there. Talking programming this was probably caused when a value that was passed with sensors was changed.
If I'm understanding things correctly. Sensors used to be a flat value, and unlimited range when you stack them. Only limited by hull size, and sensor size. Now they have a cap. Sensors may now work of a percent, not a flat value.
Or this might have been caused when they wrote 1 gigabyte class to make sure the computer does not know undiscovered territory.
Remember this is my guess. Classes share values.
Another possibly variables are global not local. I know they don't do global variables anymore, but this is based on a old game.
Ships not exploring territory they pass through is annoying, especially when this causes you to miss anomolies.