Originally Posted by ldolse
It's because the image is inserted into it's own html file (you mentioned seeing this in Sigil). Each html flow will have page breaks around it. I see this sort of thing when someone converts the file using Calibre - Calibre's default settings insert page breaks before <h1> and <h2> tags, and then Calibre splits the file on page breaks. This is separate from the Chapter detection settings. You mentioned using Calibre at some point, so I suspect you may be doing some conversion for some reason. You need to tell Calibre not to insert page breaks at those points before you use it for conversion.
But how does one "tell Calibre not to insert page breaks at those points......"?