Vistoli's conjecture on the kernel of equivariant Riemann–Roch

Let $G$ act on $X$ with finite reduced stabilizers. Write

$$\tau_X^G:K_0^{'G}(X)\longrightarrow A_*([X/G])_{\mathbf Q}$$

for the equivariant Riemann–Roch map, and let $\alpha$ lie in its kernel. An element $\epsilon\in K_0^G(X)$ has every non-zero rank if it is represented by a complex of locally free sheaves whose homology is non-zero at the generic point of every subvariety.

Vistoli's conjecture. If

$$\alpha\in\ker\!\left(\tau_X^G:K_0^{'G}(X)\longrightarrow A_*([X/G])_{\mathbf Q}\right),$$

then there exists an element $\epsilon\in K_0^G(X)$ with every non-zero rank such that

$$\epsilon\alpha=0.$$

The conjecture describes the kernel of the equivariant Riemann–Roch map when the quotient has finite reduced stabilizers. The supplied source does not state whether it has been resolved.