Issue Summary

After upgrading from 6.13 to 7.4.1 and a full content reindex, the customer noted that they were no longer able to see new indexable actions show up in the UI (cannot search for newly generated content, etc). Full content reindexes from scratch work fine, but the actual scheduled job for ongoing index operations is not working.

Steps to Reproduce

1. Upgrade from 6.13 to 7.4.1
2. Perform full content reindex

Expected Results

New content that is generated should be indexed after the latest content reindex.

Actual Results

New content that is generated is not being indexed after the latest content reindex, so anything that depends on index updates in the UI are not available to retrieve the new content beyond this point. 

Nobody is currently able to search newly created content beyond the time of the content index being rebuilt. All production users are impacted as a result, with a user pool of 8.5k accounts.