EDIT: This should now be fixed with version 2.5. See here: viewtopic.php?f=35&t=15961
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The guys from OMDB are under some kind of attack causing FlixTools not being able to retrieve metadata.
This is the message they posted earlier today on their website:
and some stats:
FlixTools works and it normally downloads subtitles etc. but the main issue is with Add to iTunes. As a temporary alternative, you can always add Metadata manually (click the 'edit' icon in the top right).