[ldolse]

There are several cases where formatting data can get lost during conversion and there is nothing that can be done about it with the conversion engine that wouldn't require a monumental effort. That's because mobi can break all sorts of modern html rules, and in order to get to epub it's got to be converted to valid xhtml. The mobi markup is massaged before converting to xhtml to prioritize what will be kept vs. lost, but in some mobi files the rules get broken so badly something will get dropped (formatting, not textual data).

Regarding the OP's complaint though, this is just a Calibre viewer issue - it doesn't display/create page breaks from mobi files during it's conversion to OEB for the viewer - I don't believe Kovid has any plans to address this, but fully converting to epub and viewing that will fix this problem.