Blank pictures in cover shows
Sometimes some shows display a white cover, as the image shows.
This means that the cover did not download correctly, and the cached image is corrupted. The current version of TVShows does not detect this situation, and it does not fix it automatically.
The easiest way to fix it is by clicking on that cover so that your subscription details appear, and then click on the green arrow that appears in the bottom of the cover. That way the cover is refreshed, as seen in the image above.
If a lot of those images are blank and you want to avoid doing
it for every subscription, you can delete the cached images to
force TVShows to download again the good cover. These images are
2/Cache. To access it you may need to copy that in the
Finder Go menu -> Go to folder option, since
the Library is hidden in Lion. Then, you can delete all blank
covers you find there.