This is probably a relatively niche issue, but one that is worth highlighting for anyone in governmental settings using both SharePoint and Fabasoft (ELAK), but will share it here as I know others who have had the problem.
To use drag and drop from Outlook, (as well as into Sharepoint) I have to have the DnD to HTML5 Addin for Microsoft Outlook plugin activated.
Otherwise you can't drag a word file etc. into Studio from Outlook (ie. if the plugin is not activated DnD only works into ELAK).