Yikes! You are having a nightmare. The problem, though is that even if I did that I would have to save the whole video file when I only want small portions of it. I ordered the new gopro4 today. We’ll see if that has the same problem.
Unfortunately it doesn’t seem to matter whether I import from the camera or the card reader in my Mac. I have found that if I import without optimizing the media, that helps sometimes, but I have found I have to import the segments then duplicate them in the finder and drag them into the import window. That is the only way it seems to work. When I import from my Canon, no problems.