I'm only using quest bot, so I don't know if the following problem extends to GB2, if it's just QB or if it's HBCore, but it seems like the bot is not fighting mobs back when trying to harvest a node, and will only "snap out" of it once a defensive cooldown triggers (like in my DK's case, Rune Tap).
It should be easy to replicate, but if you need a log let me know and I'll get you one later. I have disabled gathering for now.
The bot will eventually fight back, but running to a node and standing still for 10 seconds before turning around to hit a mob, on my full server is, at the very least, quite risky to let go unsupervised.