Originally Posted by miwie
OK, doing the following seems to do the job:
- add cover into metadata
- convert (again) to EPUB (exporting does not work)
Exporting works most of the time. It depends on whether the cover can easily be identified (e.g. Mentioned in the toc.ncx file inside the epub). Conversion should only be needed if Calibre has to analyse the book to try and identify the cover.