Gongyo's log-canonicity conjecture for ramification divisors

Let $X$ be a smooth projective variety and let $f\colon X\to X$ be a $q$-polarized endomorphism, meaning that $f^*H\sim qH$ for some ample divisor $H$ and integer $q>1$. Let $R_f$ be the ramification divisor defined by

$$K_X=f^*K_X+R_f.$$

Gongyo's conjecture. After replacing $f$ by an iterate, the pair

$$\left(X,\frac{R_f}{q-1}\right)$$

is log canonical. The conjecture is known in dimension two except possibly when $X\cong\mathbb{P}^2$ and the sum of all $f^{-1}$-periodic prime divisors is zero; its general status is open.