Weak equivalence preserves exponents of p-adic differential modules

Let $I$ be an open polysegment, let $P$ be a $\nabla$-module over $A^n_K(I)$ satisfying the Robba condition, and let $A$ be an exponent of $P$. A multisubset $B$ of $\mathbb{Z}_p^n$ is weakly equivalent to $A$ in the sense of Definition. Exponent-preservation conjecture. If $B$ is weakly equivalent to $A$, then $B$ is also an exponent of $P$. The converse is known when $A$ has non-Liouville differences, but it is not known in general whether weak equivalence always preserves being an exponent.