An item was not published, however, we expect it to be published!

Item was not published usually means changes cannot be seen in the live site.

An old information might be shown from the HTML cache/indexes/browser cache/CDN, whereas an item could physically exist in live site database and it is wrong to blame publishing.

Zero step is to check the existence of an item:

Select * from Items where id='missing_item_id'

If nothing is physically stored in the database, it is a time to start the investigation.

1. Item change was not detected by publishing mode
2. Item change was skipped (publishItem pipeline responsibility)
3. Publish operation was not executed (Another publishing was executed, and your one is still in a queue)

Sitecore can be configured to write additional information into logs to provide more insights.

A) Output more publishing-related information by setting DEBUG log level:

<root>
  <priority value="DEBUG"/>
  <appender-ref ref="LogFileAppender"/>
</root>

<logger name="Sitecore.Diagnostics.Publishing" additivity="false">
  <level value="DEBUG"/>
  <appender-ref ref="PublishingLogFileAppender"/>
</logger>

As a result, Debug messages would be printed to logs.

B) Setting 'traceToLog' for UpdateStatistics processor in PublishItem pipeline:

  <processor type="Sitecore.Publishing.Pipelines.PublishItem.UpdateStatistics, Sitecore.Kernel" runIfAborted="true">
    <traceToLog>true</traceToLog>
  </processor>

Sitecore will output reasons for picking specific operation:

INFO ##Publish Item: Name=__OnSave, Uri=sitecore://master/{62B79128-155C-4210-A4D2-EEC62BB51603}?lang=en&ver=1, Operation=Skipped, ChildAction=Allow, Explanation=The source and target items have the same revision number.

INFO ##Publish Item: Name=Sample Item, Uri=sitecore://master/{56F6D1D9-DBB1-414F-BF45-E7FC8503EE74}?lang=en&ver=1, Operation=Updated, ChildAction=Allow, Explanation=Version 'en_1' was published.

C) Setting 'high' event timing level

  <events timingLevel="high">

This would force to write time spent for processing each event, and would pinpoint to code slow parts:

INFO Event ended: item:saved. Elapsed: 42.32

Once Sitecore is configured, publishing can be triggered to reproduce the issue, and collect diagnostic information.

Load resulting Sitecore logs into Log Analyzer, and set string filter to item id:

Item changes were picked by publishing, but the item was considered as unpublishable due to a lack of publishable versions.

Locating publishing restrictions for the item via SQL query results in one row:

C61E96C1-D6B4-400E-A444-D4FF80839217 Am i draft __Never publish 0 shared 1 2017-08-08 07:09:08.423

Item has Never publish checkbox set that is preventing it from being published.

Let`s locate item versions in final workflow via items_in_final_workflow.sql:

Item does not have any items in final workflow ff query did not output any results.

If a publishable item was not published for some reason, it is a time to compare processor list in publishItem pipeline with a clean Platform.

If some items are still not published with stock publishItem, and publish pipelines, it is time to reach Sitecore support.