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After listening to the people here and reading the ESR compatibility list I tried the Verbatim brand and what do you know: Rogue Galaxy and even FF12 work fine. I guess ps2 really is picky about what brand of DVD it wants, never encountered such a case with other old consoles so I didn't know what to expect here. Even other games that showed slight loading problems now work even better.
Kinda feel like an idiot now. I guess I gotta follow instructions to the letter sometimes.