Yesterday one of our clients had an incident, all of their products disappeared from the website (like if they were unpublished). The first approach was to check if some integration has got them unpublished or some permission was wrong. After some investigation we found out that the reason that caused this was the search indices so I just rebuilt dem from backoffice and everything was ok again. Note! This happens for the first time in 2 years in this specific solution.
So my question is what are the most common reasons for such problem? What I know the search indices get updated automatically, so why? what could prevent the search indices from being updated or rebuilt? I have tried to search for something in the logs but without any results.
Litium version: [7.2]