Importing Illustrator files: no grouping and elements missing

When converting Illustrator files to Express, the elements either lost their structure.

Which means: no layers, no groups, no clipping masks.

Text objects got separated into lines, but sometimes not. It is unclear what makes them get separated.

When I first made a symbol out of elements I wanted grouped, they weren't imported at all.

When I left the expanding of appearances to Express (and didn't do it ahead of importing, then colors were off for objects that had a classic 3D effect applied.

Hidden layers get imported as well, so that I need to delete everything that I do not want imported. Or move it outside the artboard.