Hi AUCKLAND,
My apologies for the late response. Following our investigation into this matter, we have determined that the issue is likely attributable to a recent Outlook/Windows update. While dragging attachments from within an email may be affected, we have observed that dragging documents from the local computer continues to function as expected. As a temporary workaround, you can address this by dragging the entire email into the InTray, which will successfully upload all attachments contained within the email.
Please do let me know how you go on this,
If my response has answered your enquiry please click "Accept as Solution" to assist other users find this information.
Regards,
Earl