Fillet does not render for small features

I work with small structures. When creating a cube with 6x6x5 µm length and then adding a 1 µm fillet to the top boundary, the fillet does not render in photoworks. I suspect it has to do with the small dimensions  but I cannot figure out what setting I have to change to make it work.

Layout:

Rendered:

SolidworksPhotoview 360