they crashed, for different reasons like internet gone for 1 sec an image download crashed!
you can right click on them and delete the image, then Repair alert will appear on top of the comic panel, click on it and it will download image again.
and by the way do not forgot to use the latest version :)
sooo that maybe mean the site does not have image to download, this problem is common in xlecx because some of it comic does not have image uploaded!
Is That Comic Downloaded from xlecx? or nhentai?
and if you don't mine, please give me the comic name so i can check if there is any error or bug going on, and your app version :)
