Have you quested manually at all?
The quest that the bot is trying to pick up is what's called a "Breadcrumb" quest.
As explained by the
Question and Answer thread - questing manually can cause issues and isn't typically advised.
Breadcrumb quests are the main culprit as to why questing manually isn't advised because they are a type of quest that will "phase out" if you complete
other quests before it.
Sometime after Legion, I'm planning on reworking the logic used for Breadcrumb quests to hopefully prevent this.
As of now, there's no support for 'phased breadcrumb quests' - and your only solution to work around it is to manually remove the code for the quest from the profile.