Help please layout problem

using sk-2016 pro and layout 2016

i have started a layout drawing based on the sketchup 3D model. progressing towards the construction tender set.
on 2 of the drawings when i went back to amend and edit them the line tool will NOT display the lines. it shown up as a dashed line as i draw it and then disappears,on the other sheets in the same set the lines show up but not on the last 2 sheets.
these were also generated by copying from a previous sheet within the same set to save time.
i have re booted the mac twice with not change. checked the setting in the shape styler to see what has been toggled on and off on the other sheets, then set the same for these sheets but no effect. could i have accidentally toggles a setting, also why only the last 2 sheets.

all help will be greatly appreciated as i have a deadline on this project. which is usually the case !

thanks community.

Do you use Layer?
Upper layer hides lower layer.