What is the scope of the §2255(e) saving clause? And is it permissible for Zater to proceed thereunder?

Question Presented for Review The Fourth Circuit recently held: "The Supreme Court should hear this case in a timely fashion to resolve the conflict separating the circuit courts of appeal nationwide on the proper scope of the §2255(e) saving clause so that the federal courts, Congress, the Bar, and the public will have the benefit of clear guidance and consistent results in this important area of law." United States _v_ Wheeler, 2018 U.S. App. LEXIS 15753 (4th Cir. June 11, 2018). The clarion call issued on this Court was in response to the Fourth Circuit's holding in a previous iteration of the same case: United States v Wheeler, 886 F.3d 415, 428 (4th Cir. 2018)("§2255(e) must provide an avenue for prisoners to test the legality of their sentences pursuant to §2241, ... as well as undermined convictions"). Yet the Eleventh Circuit reads "the saving clause of §2255(e)" much more narrowly. See McCarthan v_ Dir. of Goodwill Indus-Suncoast, Inc, 851 F.3d 1076 (11th Cir. 2017)(en banc) (holding that claims of actual innocence, being sentenced over the statutory maximum, and being sentenced for a non-existent offense can no longer be brought pursuant to the saving clause; the saving clause may only be satisfied under the limited circumstances when the sentencing court no longer exists, or a prisoner's claim concerns "the execution of his sentence"). /! Although Zater was convicted in the Fourth Circuit, he is statutorily mandated to file a saving clause petition in his district of confinement, which is in the Eleventh Circuit. Zater would have received relief in his district of conviction, but he cannot receive relief in his district of confinement, due to this circuit split that has developed. The Question Presented is: What is the scope of the §2255(e) saving clause? And is it permissible for Zater to proceed thereunder? 1/ The remaining circuits have entrenched this split as well. See infra.