Hidden objects in viewport

[taffcad]

Can anyone tell me why in a viewport some of the lines are not visible. I can see them in the Model but not on the layout. All the layers are open and nothing is off on the plot section of layer control.
Any advise would be greatly appreciated.

 

[borgunit]

You can control layer visibility in viewports with the VPLAYER command.

"Everybody is ignorant, only on different subjects." — Will Rogers