Families that intersect in an arithmetic progression

For $n\in\mathbb N$, let $μ_n$ be the uniform measure on $2^{[n]}$. A family $\mathcal F \subseteq2^{[n]}$ is called $k$-AP-intersecting if $F_1\cap F_2$ contains a nonconstant $k$-term arithmetic progression for every $F_1, F_2\in\mathcal F$. Writing $m_k$ for the supremum of $μ_n(\mathcal F)$ over