Artin's supersingularity conjecture for K3 surfaces

Let $k$ be an algebraically closed field of characteristic $p>0$, and let $X$ be a K3 surface over $k$. The Picard rank of $X$ is the rank of its Picard group, and $X$ is supersingular when its formal Brauer group has infinite height, equivalently when the slopes of Frobenius on

$$H^{2}_{\operatorname{cris}}(X,W(k))$$

are all equal to $1$. Artin's conjecture. The surface $X$ has Picard rank $22$ if and only if it is supersingular. This is a cohomological characterization of K3 surfaces with maximal Picard rank in positive characteristic; the supplied text does not state whether the conjecture has been resolved.