anything violating the uniqueness theorems would be fair game: asymptotics, higher dimensions, modified gravity… But getting an explicit counter-example seems pretty hard. Would be nice to have some local existence proof though not sure how to even approach that!
Yeah, I might ask around. I am beginning to feel like it’s not actually true without assuming global properties though. If it were something you could prove locally, then there aren’t really *that* many ways you could approach it. So I feel if it were true, it’d be known by now