I have three things going on here when working with imported curves. I guess one is definitely a bug. (You can choose which one...)
1. Extrude wants to extrude in the wrong direction and I can't change anything here.
2. I can extrude all connected segments, one segment, but not two, three, or four segments.
3. After extruding a segment all curves are hidden and I have to break the link in order to be able to turn their visibility back on.
