I never noticed this as an issue until SW12.    Lets say I have a part in an assembly: Part1, I open the part and save it, not as a new part but change name of existing to: Part1A, the name of that part in my assembly design tree will not change.  If I look at component properties I can see that the component name is still: Part1, however the component description does show the new Part1A.    I have just manually been retyping the new name in that properties box to have it change in my design tree.  The other issue is that if I have multiple Part1's I have to do this for each part.  

GP