Complete non-ambiguous trees (CNATs) are combinatorial objects which appear in various contexts. Recently, Chen and Ohlig studied the notion of leaf permutation on these objects, and proposed a series of nice conjectures. Most of them were proved by Selig and Zhu, through a connexion with the abelian sandpile model. But one conjecture remained open, about the distribution of a natural statistic named determinant. We prove this conjecture, in a bijective way.