I’ll start with the issue: Razor Hill is phased with Alliance and Horde and there is a quest, This Ain’t Mine available, but accepting and doing the quest, the character to turn in the quest does not spawn/isn’t there. I’ve known about the phasing for a while but but it’s never bothered me until i tried to do one of the brewfest quests. I’ll also point out that every quest before and after this quest in the questline comes back completed when using the script listed with every quest on wowhead.
I found this topic: This Ain't Mine and this time It shadowlands Intro not blame - #20 by Vrakthris which appears to have others that were seemingly in the same boat resulting from a bug that uncompleted the quest and was fixed but wasn’t retro active, according to a post from Vrakthris.
Hoping posting here may get it fixed as opening a ticket has not given me a solution, even though I believe the second reply genuinely tried to help and i’m trying not to pull my hair out at this point.
Please let me know any additional information you may need.