T'Challa spent five years in the future. They traveled back through a wormhole, but in effect they still were gone from earth at least a few months. He's a changed man.
Shuri #1 shows him and Manifold leave, and it's already been two weeks with them missing, in the
same issue, and that was October 2018!
tweeks.jpg
Think of it this way: T'Challa helped in X-Men Red, which was a few months before, real time. So, he was gone during the entire Dissassembled/AoXM era. And then Krakoa was founded, he's still gone. Then he returns(must be months later, long enough for Shuri to rebuild a new golden age), Storm helps win his war(still unrevealed in Coates remaining issues).
Sometime after that T'Challa becomes chairperson of the Avengers(and thus ensues Aaron's run) while Storm does her thing in HoX/DoX. So Coates stories of their relationship with Nakia is months removed from the present, and they've both been busy globe-trotting with their respective teams, not spending any time together, when Vita's Marauders picks up.