Suddenly I get the message Unable to open Assets/XXXXX.fbx: Check external application preferences. when I select an fbx file. Also if I import a .blend file, it takes me to blender when I click on it. I tried uninstalling and reinstalling Unity as best I could, but the problem remains.
Also, I have the same problem. Previous versions open my fbx file appropriately. In 2017.1.1f1, my file shows none of animation and bones.