Shapefile from autocad civil 3d 2019 wont allow me to add fields to the Attribute table

[JoshBryk]

A Shapefile that was "mapexported" from autocad civil 3d 2019 wont allow me to add fields to the Attribute table. It will allow me to click add field, but when the field menu pops up, no new field has been added, and the "Add Field" button at the top of the screen has been grayed out. Is there any way to add new fields to this shape file? I need to create new fields and add text into the attribute table.

[JoshBryk]

After opening a blank map and checking, it definitely does not update my shapefile, so I need to find a way to extract this new layer as a shapefile next.

[DanPatterson]

You have to create a new shapefile.  

Copy Features or FeatureClassToFeatureClassTool

The only way you add stuff to an existing file is within an edit session.

[DanPatterson]

The new layer will be retained with the project.

Do you really have a need for shapefiles?  And if you do, make sure that you have them within a folder in your project workspace folder because things will go bad if you try to move things around.

Good practice would be to keep files (featureclasses) in your project's geodatabase.  Use your project's scratch gdb for junk.  Make folders in your project's path to store other data (eg images, shapefiles, text, csv or spreadsheet files).