Import Hollow-Core plank section
Make sure that within the DWG file, the Hollow-Core plank is turned into a 'region'. Additionally, the voids created by the cores must be subtracted from the ‘region’.
Under ‘Concrete Extents’ > ‘Typical Section’ > Select ‘Polygonal’ > Click on ‘Edit Vertices' > ‘Import from DWG’ > select the highlighted Hollow-Core section > OK to finish.