If an element is missing from your printed job, it may be that some fill or outline colours have been set to overprint, as this causes them to alter or disappear on the final printed job.
Alternatively, the artwork may contain multiple transparencies, or transparencies with spot or RGB colours. Artwork containing a transparency on top of a transparency, for example, text with a drop shadow on top of a semi-transparent fill, or a transparency on top of either spot or RGB colour, then this may not print as expected. When files are processed through our workflow, transparencies are flattened and spot / RGB colours are converted to CMYK, so if both are present the software may not produce the desired result. This issue can be avoided by removing multiple transparencies and using CMYK colours only in your file.
Also, any text added on top of an existing PDF using the typewriter tool will not show up on the printed job. Instead, make any amends to the original artwork file and convert to PDF.