When uploading a PDF to YUDU Publisher, users may be prompted that the PDF has unsupported elements such as smooth shade or transparencies (outlined in the File Specifications Guide).
A side effect of this is missing pages within the Pages section, however the reason for the removal of the pages is typically presented in the Files menu to the right of the PDF.
In order for the pages to show, the PDF must be optimised according to the file specifications, and should this not be achievable the easiest option would be to flatten the page within Adobe Photoshop or any suite that can open a PDF to save as a flattened PDF.
To flatten the PDF in Adobe Photoshop, open the PDF and click File - Save as. From here, you are presented with the following dialogue box:
Ensure that the Layers tickbox is unticked and save the file format as Photoshop PDF, clicking Save to progress.
In the next dialogue box there are various options to be selected, however the main concern is the compression window - you may wish to test this with the following settings:
Following this dialogue box your PDF will be saved in the location you specified earlier in the process. Navigate to this file and run optimisations in Adobe Acrobat - a profile to use can be found in the following guide to optimise: