Fomin–Zelevinsky's Laurent positivity conjecture for F-polynomials

Let $\mathbf{\Sigma}$ be any cluster pattern with initial point $t_0\in \mathbb{T}_n$, and let $F_{i;t}(\mathbf{y})$ be an $F$-polynomial in that pattern. Fomin–Zelevinsky's Laurent positivity conjecture. Every $F$-polynomial

$$F_{i;t}(\mathbf{y})\in \mathbb{Z}[\mathbf{y}]$$

has no negative coefficients. This is the positivity conjecture considered alongside the constant-term and sign-coherence conjectures for cluster patterns; the supplied source does not state whether it has been resolved.