Post Indexer in WP Engine envrionment

The required tables have been added to my database. Post indexer seems only to do something when I run it manually. I have tried uninstalling and reinstalling. I manually indexed on Sunday and again yesterday. However, there are about 100 items a day posted to the multisite and they are not showing up in the post widget or global rss feed. WhenImanually re-index, they do.

Where to start trouble shooting? This was all working until the last post indexer update, as I recall (lasttimeposts were updated in the global feed prior to this Sunday was May 25th).