Disappearing surface fills & curves when trimming surface

Hi everyone,

I’m having trouble with the drape surface i created for my topography. When i trim or split this surface the surface disappears on the edges of the surface boundary (see image below). Also when I projected the curves of my road on to the surface, its missing in some parts. (see image below). Is it because i manipulated the topography surface with the points to match the topography i need for my project? Thanks in advanced!


It looks like a display mesh issue. Perhaps this will help.

Worked like a charm! thank you!