Do you see the award animation after you try to receive the award? If you do, this is a common bug that get's fixed every server check or every server self-update. It happens with many quests and not just a particular one.
Try Assigning your NPC Chat key with a button on the keyboard. When you are close to the NPC try spamming it. If that doesn't work, try again after some time. Not sure if changing channels and relogging helps, but you could try those options as well.
There is nothing different being sent when assign the NPC chat key to your keyboard besides the key being added to your keymap. It doesn't change anything else. I've tried changing channels twice. No difference.
I think he means you can retry faster if you are using your keyboard. But I have found that spamming does not work. He is unknowingly talking about a different glitch if spamming is suggested. Sometimes the quest does not give you the award until the second time you ask for it. This seems to be a different glitch than the one where multiple quests cannot be handed in by everyone. Edit: Just give it a day or two, or try right after a server check.
For some reason, using NPC chat, direction keys and Enter rather than clicking on the NPC used to work. However, it hasn't been doing so in quite a few cases recently. I am pleased to report, however, that our developer is making good progress with the questbug issue.