To my knowledge there doesn't exist a $O(n)$ worst-case algorithm that solves the following problem:
Given a sequence of length $n$ consisting of finite integers, find the permutation where every element is less than or equal to its successor.
But is there a proof that it doesn't exist, in the transdichotomous model of computation?
Note that I'm not limiting the range of the integers. I'm not limiting solutions to comparison sorts either.