After thorough testing and observations from what I was experiencing with Arch buddy today (per my quoted post above), I believe I have found the source of the bug.
The "spell" "Survey" has a cooldown of 3 seconds. It seems that if it's next survey point is very close, like maybe 1 or 2 yards away, it will move to next point and attempt to use "Survey", but "Survey" is still on cooldown.
This is the exact point the bot will exhibit the behavior I mentioned, never finding the next artifact and just going crazy until I stop the bot. This weird little bug is ruining the AFK-ability of AB.