Edit Report Based on Large Dataset

I am aware that you cannot download a .pbix copy of a report that is based on a dataset that is saved as a "large dataset storage format". I am probably just using the wrong search terms but what I cannot find is how one goes about editing or working with such a report, assuming the original is lost. The option to download the .pbix file is available in the menu but it fails to download, so it's not a matter of tenant settings.