Currently Being ModeratedOct 24, 2013 10:50 PM (in response to Thomas Emmerich)
And it works with iMessages.
After enabling the previews in Aperture's preferences you need to generate them. The previews settings will only automatically create previews for new photos. To generate them for older images, use the command "Photos > Update Preview".
How large are the images, that you try to drag? For very small images Aperture will not create previews at all, if the images have not been adjusted.