No offense, but I'm thinking it might be just you, or maybe something weird with the stencil you're using. What stencil are you using? Is this a new document, or maybe one where you made some canvases read-only (so they won't accept a drag n drop)? If those ideas don't help you fix the issue, maybe send an email to the Graffle Ninjas at
omnigraffle@omnigroup.com