Last modified: 2014-01-10 18:34:58 UTC
Sometimes the metadata info is missing, even though the API request seems successful. This happens randomly, and seems to come in batches (when using prev/next, if an image is affected, several neighbors are, too). Spotted on beta enwiki.
Change 106480 had a related patch set uploaded by Gergő Tisza: Fix metadata loading https://gerrit.wikimedia.org/r/106480
Change 106480 merged by jenkins-bot: Fix metadata loading https://gerrit.wikimedia.org/r/106480
I believe this is fixed now, especially with the promises patch. Thanks!