Does the Alleyne rule apply retroactively on collateral review?

QUESTIONS PRESENTED 1. Does the new rule of constitutional law announced in Alleyne v. United States, 570 U.S. 99 (2013), that any fact that increases the mandatory minimum sentence is an "element" of the offense and thus must be found by a jury, rather than a judge, and must be found beyond a reasonable doubt, apply retroactively . on collateral review, either because it is a substantive rule or a watershed rule of criminal procedure? 2. If Alleyne is not a substantive rule but is a watershed rule of criminal procedure, are the states constitutionally required to give it retroactive effect, a question this Court explicitly left open in Montgomery v. Louisiana, 136 S.Ct. 718, 729 (2016)? i .