Missing part in viewer

Hi All,

Im having this problem whereby it seems that there is one missing part of the print in grey where everything else in blue is printed correctly. Im not sure whats the problem because its a repeating structure but Cura just seems to skip that one part and moves on to the next.

For more information, the structure is consist of two trianglular extrusion (with both intersecting each other in a sort of hourglass shape)

Thank you so much !

EDIT: this is the link to the part