[FlaSheridn]

Originally Posted by Starson17

It just didn't modify the content of your EPUB and that's because your EPUB format could have come from any one of a dozen or more different possible "source" files in the book record.

Ouch. I see why that makes sense from the developer’s point of view, but from the user’s perspective it’s a serious design mistake, since in the base case there aren’t a dozen formats. The user has only used one input format; the rest are an internal implementation detail. It’s also a user interface bug, since it ends up requiring different actions to achieve the same result a second time. Even if it’s not fixed, both behaviors need to be documented conspicuously.