Hi folks, I have been digging for answers on this issue, but all I have found is this post from ten years ago with no replies: 

Here is my issue: the hydraulic motor and quick disconnect fittings are showing in the section view even though they are on the wrong side of the cutting line. Last time this drawing was released, they were not visible. Only one of the fittings is selectable in the graphics view; the other fitting and the motor cannot be selected. This has persisted through rebuilds, restarting SolidWorks, and restarting the system. This is also happening on other machines in the office.

I had some trouble on this particular drawing with visibility of other components: During work on the model, I had hidden the chain guards. After that work was done, I unhid them, came back to the drawing, and found that they were not visible. I found an extra display state with the guards hidden, so I deleted it (only one configuration in this assembly). When I came back to the drawing, the guards were not visible, but they were selectable in the graphics display. This seems unrelated to the motor and couplings showing on the wrong side of the cutting line.