Most issues having to do with missing or cut off content have to do with insufficient space allotted for content.
If the blurb contents exceed a single page, they will be cut off and not spill over onto the next page. This is most common with a series of large images. Simply divide the contents into smaller portions that can be placed into individual blurbs (i.e. image1 in blurb1, image2 in blurb2)
If the blurb space is shorter than a full page and the contents are still cut off, it means that the PDF generator has not calculated the spacing correctly. Occasionally this happens with non-traditional text. Try adding a line break by hitting "Enter/Return" to let the PDF generator know that a new line has started and to allow more space.
See this article for more general information:
PDF Troubleshooting and Common Issues
If you encounter further issues, please contact Support.