Sierakowski's ideal-separation conjecture for reduced crossed products

Let $(A,\Gamma)$ be a $C^*$-dynamical system with $\Gamma$ discrete, and let $\Gamma$ act on the spectrum $\widehat{A}$ of $A$. The action is essentially free if the points with trivial stabilizer are dense in every closed invariant subset of $\widehat{A}$. The algebra $A$ is viewed as the canonical subalgebra of the reduced crossed product $A\rtimes_r\Gamma$.

Sierakowski's conjecture. If the action of $\Gamma$ on $\widehat{A}$ is essentially free, then $A$ separates the ideals of $A\rtimes_r\Gamma$.

The conjecture asserts that every ideal of the reduced crossed product is determined by its intersection with the coefficient algebra $A$. The paper explains that its theorem gives a negative answer, so the conjecture is refuted.