Please follow the steps below to resolve this issue:
To do this go to the user login email (top right) > 'Account Settings'
Toggle the 'Verify documents before bundle is generated where possible? to Yes > 'Update'
Generate the bundle again, you should then get an error message asking you to look for a highlighted document.
Once you locate the highlighted document. You can use the 'Original Document' in your Bundle. To do this go to 'Document Settings' > 'Advanced' > tick the option 'Use original document in bundle?' > click 'Update'.
NOTE: This option is only available to be used on PDF documents. 4. Then generate the bundle again and the full bundle should now generate.