After the changes for First and Third person, I Can’t see my Gun anymore, even with 'Only Owner See" check box selected. I can only see the gun now when I eject the view with F8 key.
The problem has been solved in lecture 266 - Separating Firing from Gun meshes. I don’t know what caused the problem, but after the delete and new skeletal mesh created, the problem has been solved. Maybe was an Unreal 4.17 cache glitch.