Our image styles are not getting created on one of the Drupal 7 sites in a multi-site installation. They are created for at least one of the other sites that uses the same Drupal 7 core.
Symptoms: Upon uploading an image to a node, the image preview does not get displayed (depending on the browser, a broken image placeholder may display). The image is not created in the file system either. I have verified file system ACLs. Both sites use the same .htaccess.