The grabbable rat in the burrow at 65,88 thats needed for this achievement seems to be bugged and doesnt give credit when picked up. The other 4 rats are fine and its just this one that seems to have an issue. Looking at the wowhead page for this achievement, others seem to having the same issue.
Of course this not working is blocking the overall zone achievement for the campsite since its needed for that one.
Thank you for your attention to this matter!