The problem is not caused by a bug, it is issue related to the lifecycle status of the related images. Republishing the Master version of the images solves the issue.
sender, EventArgs e)
LibrariesManager librariesManager = LibrariesManager.GetManager();
librariesManager.GetImages().Where(i => i.Status == ContentLifecycleStatus.Master).ToList().ForEach(i =>
You can find a code sample above. Put it on the code behind of a Web Form and run it once.
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