Mutation theorem for crepant curves with perfect universal sheaf

Let $C_i$ be a crepant curve on a $3$-fold $X$, and suppose that its universal sheaf is perfect and that $X$ has at worst Cohen–Macaulay rational singularities. Mutation theorem for crepant curves. Under these hypotheses, the mutation functor theorem stated in the paper remains true. This conjecture proposes extending the mutation–flop correspondence beyond the Gorenstein setting; the source gives no proof in this generality.