From page 9 of the grasshopper connection user guide:
"Preview Option in Grasshopper's Display Menu
Most components of Grasshopper-Archicad Connection generate a detailed preview in Rhino, using colors that match those of the Archicad model. However, generated Library Parts (Object, Window, Door) display only a bounding box as a preview, by default. (Otherwise, the high polygon count might affect performance.)
To see a detailed preview of Library Parts in Rhino (instead of just the bounding box), turn on the Detailed Archicad Preview toggle in Grasshopper’s Display menu."
Felipe Ribeiro Cunha
AC 26, macOS Monterey