Originally Posted by kovidgoyal
Your original epub will have something broken like a guide entry that refers to the first content html as a cover.
Thanks. After a few experiments, I found that deleting the cover image from the front of my original document file* and then adding the cover later from within Calibre prevented the generation of the broken TOC entry.
*DOCX filed converted to ePub using the Atlantis word processor feature, followed by ePub-to-ePub conversion in Calibre to rub off a few rough edges such as the comma-delimited tags coming out as one big tag in the original ePub.