hannesmannerheim
commented
8 years ago thumbnail generation seems to be broken on your instance. the images displayed in the default gnusocial ui are actually the full size images.
so this is a gnusocial issue.
btw new qvitter issue tracker is at https://git.gnu.io/h2p/Qvitter/issues
In the past, when someone posted an image, a preview has been displayed in the timeline. With recent updates, only the link to the image is displayed instead.