$n$-ary coherence conjecture for polyadic tensor categories

Let $\mathcal{C}$ be a polyadic tensor category with an $n$-ary tensor product $\mathscr M^{\left(n\otimes\right)}$ and an $n$-ary associator $\scalebox{1.15}{\textsf{\upshape A}}^{\left(2n-1\right)\otimes}$. The associator is required to satisfy coherence conditions ensuring that the canonical reassociation isomorphism on $3n-2$ objects exists:

$$\mathscr M^{\left(n\otimes\right)}\left[\mathscr M^{\left(n\otimes\right)}\left[\mathscr M^{\left(n\otimes\right)}\left[X_1,\ldots,X_n\right],X_{n+1},\ldots,X_{2n-1}\right],X_{2n},\ldots,X_{3n-2}\right] \simeq \mathscr M^{\left(n\otimes\right)}\left[X_1,\ldots,X_{n-1},\mathscr M^{\left(n\otimes\right)}\left[X_n,\ldots,X_{2n-2},\mathscr M^{\left(n\otimes\right)}\left[X_{2n-1},\ldots,X_{3n-2}\right]\right]\right].$$

$n$-ary coherence conjecture. If the $n$-ary associator $\scalebox{1.15}{\textsf{\upshape A}}^{\left(2n-1\right)\otimes}$ satisfies such $n$-ary coherence conditions that this isomorphism takes place, then any diagram containing $\scalebox{1.15}{\textsf{\upshape A}}^{\left(2n-1\right)\otimes}$ together with the identity morphisms commutes.

This is the proposed higher-arity analogue of coherence for monoidal categories. The source formulates the condition as an anticipated requirement, but supplies no proof or resolution.