The thing I both love and hate about programming is that the computer does whatever you tell it to do. I found the cause of the star chart problem. This problem prevented more than six stars from being scanned.
The cause was literally down to one simple character ... a ">" instead of a "==" was causing any star after the sixth to overwrite the sixth star in the sector file.
It's so obvious now, but what a crazy bug hunt it has been.
The good news is that I will be able to give each sector up to nine stars again!
I will be looking at a couple other issues before I update the game again.
I will make it a bit easier to upgrade from version 2.1 to the new version. There is also an issue where previously scanned stars are appearing with a red highlight instead of blue. There are a few others, but hopefully a new update will be available later today or tomorrow...