When showing images lists using G2Image when using single sign on sometimes not all the images are shown that should be shown. If you use single sign on then all the images that the user should be able to see (based on gallery2's permissions) should show up.
If you view the gallery and then go back to the admin interface it seems that a cookie gets set and causes the images to be shown again but this should be done automatically.
Note: The reason for this is that the current integration with G2Image doesn't check single sign on and actually log the user in. So sometimes the gallery2 login can become invalidated even though the b2evolution is still valid.
Note: Should explore and see if it's a problem when viewing images in blog entries also.