Tapped Holes edges wont hide?

Hi all am quite new to soildworks and need some help please

ve created a assmbley drawing and made a secetion view which has afew parts in

when i come to hide some of the edges of one part.....whichcontains some tapped holes they wont hide....? but i can hide theother edges within the part

not sure why this is happing maybe someone can shed some light onthis?

thanksSolidworksDrawings And Detailing