I am importing a *.dgn file, and as a result I get a lot of curves, instead of surfaces/meshes. Only part of inported dgn file has been converted to meshes. Is that a limitation of Rhinocerso, or a matter of parent software export settings or something else?
First thing to try, I suppose, is to check what another application gets out of that file - you could try with Teigha Viewer [link to from Wikipedia].
Then, if you get surfaces there that you don’t get with Rhino, you will have to supply the dgn file - either by posting here or uploading to rhino3d.com/upload referencing this forum thread in the upload notes.
I’ve just uploaded a DGN file that looks fine in ODAviewer, but most of the objects are missing once imported into Rhino6SR9. I suspect those missing objects are some kind of blocks.