Hey guys, updating you on the achievement problem.
The current theory is that the problem WAS indeed, for some reason, happening after the latest update, and that walking the game through to an ending is remembered, so even if I didn't get the achievement because of a non-working patch, when I rolled back to a working one, I didn't get the achievement because the game read it as an already received one and didn't signal it to steam. Players trying out new routes after last night's patch got the achievements normally today, but if that theory is correct, you won't be able to unlock achievements for endings you already played, because the game reads them as unlocked already. My apologies to players who weren't able to unlock achievements in the time frame. From now on, for new players or routes you didn't play yet achievements are supposed to work normally.