A user creates a custom entity using the Advanced Custimistion Wizard and makes sure it has the "library" feature.
Create a new record under this newly created entity and navigate to the documents tab.
Select the option to "Add file" but nothing happens and no file is uploaded.
This issue has been resolved in Sage CRM 7.2g and it will be resolved in a future patch of Sage CRM 7.3.
In Internet Explorer 11 the "Add file" button is not visible unless compatibility mode is enabled.
In Chrome/Firefox the document drop does not work.
In Chrome/Firefox you cannot upload a file with the "Add file" button.
This is an issue in 7.2f and 7.3GA.