The add-in I am developing uses the addFileAttachmentAsync() function to attach a text file. This function works correctly in OWA, but when I test the add-in in Outlook 2016 I am seeing some strange behavior.
The addFileAttachmentAsync() call appears to succeed passing the asyncResult.status == Office.AsyncResultStatus.Succeeded check and the code within that block is executed. However, underneath the file name instead of seeing the file size Outlook says Download failed, but strangely it is still possible to click on the "failed" attachment and open it.
The URL used is a publicly accessible S3 bucket. I have one computer running Outlook 2016 where the addFileAttachmentAsync() call adds the attachment without problems, but two others display the Download failed string after adding the attachment. This behavior is consistent so it does not appear to be any type of network issue.
Is this a problem with the code in my add-in? Or is something going wrong with the Outlook 2016 clients on the other computers?