It is a bug in SDK and seems is not fixed yet. It also happened for me.
If you edit and save it inside code [not in SDK Scene Composer] it will work 99.99%.
there is one trick to make it works in SDK Scene Composer and it is to create material using sdk
I fix it in this video:
then you can edit and save in SDK scene composer without problem.
but about your first problem
Make sure to bake animation in blender then import it to JME.
if you do not know how to bake it, I created a video tutorial for that