I saw in another thread that someone gave the hint "In Sandbox mode, she can be bigger..."

But I got the Sandbox mode ending where she busts out of the building, and the achievement didn't pop. I tried everything else I could think of that might be it, and it didn't work, so I figured I was bugged. I reset the registry to wipe my save, went through into unlocking Sandbox mode again, got the building busting ending and still no achievement.

I'm on the latest windows release. Any idea? Am I just missing a trick? Or do I just have to settle for one achievement being bugged out?

btw, total agreement with others on here saying this is the best BE game I've ever played. The artwork while growing is so damn smooth, and the voice acting is great. Game is good and satisfying.

Thinking of speedrunning it, just to have more of an excuse to play it.

This was answered in the other thread.

Did you figure this out? I tried doing in sandbox mode and couldn't get it, maybe it's only achievable in one of the other game modes? bugged? Something else? I also spammed the milk increase, is that why? Am I supposed to let her expand naturally?