Took the current hex2 collab version in original post, non-contiguous paintbucketed each palette swatch in top left to cover all "legal" pixels with black, therefore proving their innocence. Only the shameful guilty pixels were left. I'm far too cool to use incorrect colors!*
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View Blinking Guilty Pixels<< 15, 33, 65, 81, 82, 83 and 84 are affected.
Don't know which other tiles may have more guilty pixels masked off; I can't see them to find them. It's noteworthy that all guilty pixels I found use colors used for the unclaimable tiles. Considering we all use different software and work differently it's not surprising. Stricter QC may be necessary.
(while we're on the subject, I just found 3 bad pixels in the hex1 collab, hehe. only 3 though)