I also have a problem/bug with this quest. Currently I am unable to see the Questgiver and accept the quest, again. A moment ago my toon was standing where the quest giver hands out the quest, I disabled all add-ons, I clicked reload on the add-on interface and my screen reloaded. No Quest giver. I typed /reload to cause my interface to reload again, and again no quest giver.
How I got here: I accepted the quest and the Extra Action Button did not appear when I was at the tall-production-cans that are to be destroyed. I dropped the quest and returned to the quest giver and accepted the quest for the second time. I returned to the tall-production-cans and the Extra Action Button did appear. Frustrated I dropped the quest and figured that I'd get the quest again the following day.
The quest giver has not come back for me. I looked for the tall-production-cans to see if perhaps I'd not actually dropped the quest but they are not there. The prior quest shows complete=true. This quest shows complete=false.
I have been in touch with Blizzard Support, they suggested the Interface Reloads I mentioned above. I will next submit a bug report (as suggested by Blizzard Support).
I solicit any ideas that come to your mind as you read this.
Thank you