Embedded PDF in fixed layout ePub

Can anyone confirm if embedded pdf's are supported in a fixed layout ePub?

If I create a simple free flow ePub (version 2 or 3), embed a pdf in the ePub and have a link to the pdf on a page in the ePub, clicking the link opens the pdf.

However if I mark the same ePub as a fixed layout the link no longer opens the pdf - instead when the link is clicked a window opens as though the pdf is going to be shown, but the window remains empty.

Is this a bug in iBooks?