While creating the profile of more than 1km, separate DGN/DWG files will be created for each km. But while exporting the DWG files need to export one by one instead of exporting all the files as shown in the below snapshot.
Steps to resolve:
1. If use working drawing tools, change in View > Configuration menu > File Management > Check on "To single Drawing as Multiple sheet Model" to create multiple sheets in the same drawing or different drawings before creating the multi page drawing.
2.If you use Final drawings options, you need to publish the drawing in either different sheets or different drawings as well.