John, I think it is the other way around. FTM is calculating that ancestor as my 43rd GGF while Ancestry is calculating him as the 19th GGF of my 21th GGF, which certainly is not the most direct relationship. The same thing does occur in FTM but very rarely. When it does happen, switching positions usually gives you the more direct relationship. Calculating down the tree seems to be more accurate that calculating up.