Billey–Pawlowski pattern-avoidance conjecture for multiplicity-free Stanley symmetric functions

Let $G_w$ be the Stanley symmetric function of a permutation $w$. Call $G_w$ multiplicity-free when, in its Schur expansion, every coefficient is either $0$ or $1$. Billey–Pawlowski's pattern-avoidance conjecture. The multiplicity-free Stanley symmetric functions $G_w$ are characterized by avoidance of 189 patterns in the symmetric groups $S_6$ through $S_{11}$. The source cites partial or subsequent work but does not state that the characterization has been proved in full.