I have an org-mode file that contains headings with attachments. When I org-mime-org-buffer-htmlize I get an error, "Need absolute `org-attach-id-dir' to attach in buffers without filename". org-attach-id-dir has the value data/. I get this error even when I am in the buffer for the file, not simply a capture buffer. This seems to come from org-attach.

The buffer name is name of the file, but not named using the absolute path to the file, is that why I am getting the error?

Looking at buffer-file-name while visiting the file indicates that the value is the full path, but local in buffer it's not the full path and the global value is nil.

Thanks