How to mass remove attachments in Thunderbird using Attachment Extractor?

I came back a day later with fresh eyes. I assumed the add-on worked and that I was missing something. My only goal was to delete attachments. But I thought perhaps it really wanted to save attachments as well. I found two settings to try: giving a default path to save attachments to (general tab >> default save path) and more signficantly disabling the saving of attachments (advanced tab >> attachment file saving >> disable saving). Setting the former made the add-on start working, doing a detach-and-save, while setting the latter then did a detach-only. Problem solved!