If you finished this quest but the script didn't start so that you can finish Bwemba's Spirit, what probably happened was that you flew on to the platform and Bwemba failed to follow you properly. Even if you finished this quest, all you have to do to trigger the event is to present Bwemba to Vol'jin by hovering over, then floating straight down from above, or dismounting and walking through the building, up the stairs.
I got it to work twice this way (on two different toons). No need to abandon quests, leave Booty Bay and come back, or any other interesting and creative workaround. Just present Bwemba to Vol'jin and you will be able to finish the event.
Quest
Making Contact
Quest facts and objectives from the current retail game data.
The highest voted Wowhead comments for this page. They are community notes, not TheWoWDB comments.
Click [toggler id=spoiler hidden]this[/toggler] if you don't care about quest line spoilers.
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[h3 first][icon name=side_alliance]Alliance[/icon][/h3][h3 first][icon name=side_horde]Horde[/icon][/h3][/div]
Making Contact and meeting Vol'jin in Booty Bay - make sure you stay there until Vol'jin is completely done talking and you see the ? go yellow over Bwemba's head. A lot of people doing this quest can make it bug out a bit.
Quest facts
The client quest POI data records no map location for this quest, so no map is shown.
Check whether you have already completed this quest
in-game: /run print(C_QuestLog.IsQuestFlaggedCompleted(29152))
Requirements
Read from the Blizzard quest API.
Description
You aren't one of the zombies... A troll? I did see one, just before the outbreak... He warned us, told us to be on our guard... But it was too late. Your troll friend headed to Booty Bay to warn them...
Community notes from Wowhead · 52 comments
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Where this quest fits
Other quests with this name
This one: Alliance only · Level 35.
Steps, storylines and map placement from the client’s QuestLine, prerequisite and QuestPOI data; neighbouring quest text is Blizzard’s own (quest API), shortened to its opening sentences.