Create a new field in the secondary entity "Document", add the new field to the "Library Web Picker" Screen and make this a required field.
Add a new document using the "Add file" option under the documents tab within a company.
Save this document without inputting data into the required field.
The document is uploaded and saves successfully, but it should have displayed an error meassage saying the field was required and prevent the user from saving the document.
This issue has resolved in Sage CRM 7.2g.