How to publish attached files?

When I attache files to a notebook, publish it and then copy it, the attached files are not in the new notebook. Am I doing something wrong or is there any trick to copy attached files?

When attaching some data in a CSV, of course, I need also the data to run the notebook. Otherwise the copied notebook is just a static report which cannot be rerun.

Best solution I could think of was to host the file somewhere and then download it in the notebook. But that’s a quite cumbersome workaround.