I was given a group of books (a series by a favorite author) that had already been given metadata information by someone using Calibre. Unfortunately, none of the original covers were included, and an annoying "jacket" page was added, and the titles were skewed - rather than First Last for Author they were all titled Last, First - Series Number, Title (year). So, I used Calibre myself to edit each and every one, added the covers etc, and when done, added to my iPad. None of the covers stuck. They all reverted back to the generic Calibre cover, And the titles etc are a mess as well. So I hacked the crap out of them with Sigil, and used iTunes to add my cover.
It was frustrating to say the least. I did a search for this cover issue, and found only one instance of it (the cover image).
What I want to know, outside of how I can actually accomplish this using Calibre, is, does there exist a metadata tag editor like mp3tag for music files? When all one wants is to get proper titles, caps and spelling, Calibre is a bit too much work. Especially if the changes do not stick.
After posting I did a search for "simple epub metadata editor" and found a real gem! No doubt it is well known but will add a link to it. It's called (duh)
epub-metadata-editor