The Code Conversion Utility did not add a class member to your class because this version of LabVIEW NXG does not support the file type as a class member.
This version of LabVIEW NXG only supports VIs as class members. The Code Conversion Utility converted the class member but the class member is no longer a member of the class. You will no longer be able to access private data or community scope members from this file.
Review the converted file for correctness. Create accessors to access data from this file outside the class.
If the previous suggestions don't restore the functionality of the affected code and the code isn't essential to the core functionality of your application, you can remove the portion of code. If the code is part of the core functionality of the application, you can use the VI Interop node to call your existing code, provided that the new code organization meets the architectural goals of your application. If neither solution meets the requirements of your application, do not migrate to LabVIEW NXG at this time.