Pages on iPad Pro - Image is Halfway up the Page in Landscape PDF

After I have imported an image into Pages to the bottom of the document and exported it as a PDF, the image is fine when viewing the PDF in portrait mode (and rotating into landscape mode without closing the PDF), but if I open the document in landscape mode the image is halfway up the page (and doesn’t change when rotating without closing).

This is an important work document, and I would like to control how the image sits permanently, otherwise, I’m going to look like an amateur. I thought exporting to PDF would make it bulletproof-viewing.

Many thanks in advance.