In a specific scenario, items in an item bucket may not be published to the Web database as expected.
This happens when the parent bucket item or specific items inside the bucket are published using the language that differs from the Sitecore Client language.
The issue occurs due to the way Sitecore internally maintains bucketed items — specifically due to using the internal structure of service items that are created only in the Sitecore Client language, preventing their child items from being published using a different language.
Set the Publishing.PublishEmptyItems setting to true in the Web.config file:
<setting name="Publishing.PublishEmptyItems" value="true" />
Note: This solution applies only to Sitecore 7.2 Initial Release and later.