[Terrace of Endless Spring] / [Temple of Five Dawns] The Emperor's Gift

[Shalahn]

Wowhead quest link: https://www.wowhead.com/quest=41003/the-emperors-gift
WoW Freakz quest link: https://www.wow-freakz.com/quest_helper.php?quest=41003&name=the-emperor-s-gift
Bug description: Hey. On my monk I reached level 98,did the scenario,then got to the class hall.I got the artifact quest(The Emperor's Gift),did that scenario too,but when I got the artifact(Sheilun,Staff of the Mists),it didn't count as credit for the quest. Then I returned to the class hall,did the scenario again,but it didn't let me get a second Sheilun,Staff of the Mists.As artifacts can't be destroyed,I am now stuck at The Emperor's gift and can't progress further in the class hall and in legion content.
Proof: https://imgur.com/7wWhjor.jpg%5B/img%5D