I came across what I think is the same problem, and here is how I am able to insert a PDF.
1) Click on the Insert (Add an Image) icon, and select the PDF you want to upload from your computer.
2) The PDF will be added to your Gallery. There, click on the link “Show”.
3) This will then expand to allow you to edit Title, Caption, Description and Link URL. Under Link URL you will see buttons for “None”, “File URL”, and “Post URL”.
4) Click on “File URL”. This is IMPORTANT as it is what will add the “link” portion of the file to your post. Otherwise, the text will simply appear in the post but with no link.
5) Click on “Insert into Post”.
Hope that helps!
-areacode514
