Missing indices error followed by missing system status page
This sounds similar to Status page angular load error and i will paste my answer here, though I think your 'question' is the wrong issue, ie this is angular issue, not missing indices issue.

We had one site that had 'lost' all it angular pages, eg CiviMail and System Status.

In our case the angular cache files were returning 404 on the New Mailing page. (and 'inspector' was showing a lot of red angular errors)

It was building the cache files in sites/default/files/civicrm/images, but then searching for them in sites/default/files/civicrm/persist/contribute

The issue here was a mismatch between the resource url setting for Image Upload URL and the directory setting for Image Directory. Strangely (!!) these folders are being used for caching of angular files.