Did you use Pkg.add to add A as a dependency to B? That would fully explain your issue since add records the current commit that repository and keeps on using that unless you call Pkg.update to change to newest version. If you want to use Pkg to just load whatever happens to be at some location on your machine you need to use Pkg.develop instead of Pkg.add.
The documentation might help you: Pkg.add and Pkg.develop