Nieraeth's maximal-operator duality conjecture for s-concave Banach function spaces

Let $s\in (1,\infty)$, and let $X$ be an $s$-concave Banach function space over $\mathbb{R}^n$. Write $X'$ for the associated space of $X$, and let $M$ denote the Hardy--Littlewood maximal operator.

Nieraeth's conjecture. If $M$ is bounded on $X$, then $M$ is bounded on $X'$.

This conjecture concerns the transfer of maximal-operator boundedness from an $s$-concave Banach function space to its associate space. The supplied source presents it as a conjecture proposed by Nieraeth; no resolution is given here.