Oops...I went back and checked again. It turns out the smudges on my monitor were the problem. Sorry for the false alarm.
To explain, my method of solving this category of puzzle is to copy it into notepad, invert the squares that are red on the solution, then solve for the puzzle with equivalent inputs that would instead turn the translated puzzle all green. If translating to the all-green version doesn't make the solution obvious, then I check for minimum required inputs (as in, pick a corner that isn't green and look at the 4 inputs that can make it green, then recurse). In this case, that reduces the number of variations to look at down to 16, which I can easily fit on my monitor. However, all of the above is foiled if the 0's and 1's I'm using in notepad look wrong.