After sifting through 20 pages of the forum (i knew i'd seen this problem before), i have another suggestion if the tip above doesn't work. In your GP3 folder, there's a file called cards.txt and a file called readme.txt. in the readme, there's a section called flags, which you can paste into the cards.txt file. There's a flag which claims to fix cyan bits around objects, which may be what you're after.
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Team Japan Owner - GPGNC