Hello!
It seems that either documentation is wrong, or it is a bug, or there was an undocumented change in the engine since version 4.9.
Here in the docs in Permanent Attachment section it clearly states that you can permanently attach something to a socket to make it a part of the skeletal mesh.
However it does not work, you can only attach it as Preview Mesh, and you have to use blueprints to actually make that work in game.
So, what is it? Mistake in the docs, a bug, or am I doing something wrong?
Thanks.