Media files Not Sync in Staging task

What version and hotfix are you using? Are there any errors in the Event log, staging task or Windows event viewer? Are the disk permissions OK?

We using v13.0.118, there no error in the Eventlog and staging task

How big is the PDF? It may be too large to stage up https://docs.kentico.com/13/deploying-websites/content-staging/staging-large-files the limit is 28.6MB

Another problem is that its possible in your lower environment you allow PDFs to be added to the media library while in production, you do not have them allowed. Check this by:

1. Open the Settings application  (in prod).
2. Navigate to the Content → Media category.
3. Add the selected file extensions into the Media file allowed extensions setting (separated by semicolons).
4. Save the changes.

Compare the above settings on the lower envt and prod and note if they are different. Add .pdf; to prod if its missing