When attempting to close out completion of exploring BFD, it is not possible to be in the BFD "area" while within Ashenvale. When crossing over into BFD you change channels and therefore zones, making it such that BFD's completion within Ashenvale does not complete

Goign to the prescribed coordinates did not yield success in my attempts

BFD is not required for the achievement and so should be relatively harmless to just remove it from the list

Cata 4.4.1.58558
ATT 4.2.8(release)

Above extends to Razorfen Kraul in Southern Barrens