Black Blue stars are manual ratings. You can edit ratings in the most views where they can be seen, with the exception of the Album Rating column in the songs view where they're not active. Enable and expand the artwork column instead, when it is is wide enough there is an active rating that you can edit.
Dark Grey stars are auto ratings that are generated in response to manual ratings. Manually rating tracks of an album will auto rate the album if it isn't already rated. Manually rating an album will auto rate any unrated tracks.
You can suppress auto ratings with my scripts ClearAlbumAutoRating and/or ClearTrackAutoRating which set manual values of 1%. A rating of none enables the auto rating behaviour where unrated tracks are given an auto-rating that matches the album rating, and an unrated album is given a rating that reflects the rounded average of any manually rated tracks. There are corresponding scripts to reset things if you want to restore auto ratings later.
In recent months there seems to be another issue where syncing after tracks have been rated on a device may cause an album to gain a full rating in iTunes. Hopefully Apple are aware of this issue and will resolve in a later build... maybe.
Use iTunes Feedback if you want to make suggestions to Apple.
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