After indexing, or reindexing, searching does not yield results I know are there, or searching will seem to work for a time after reindexing and then stop yielding the correct results.
1) Make sure Antivirus Considerations are in place.
2) Make sure Microsoft Indexing is turned off.
3) Reindex the project.
1) Antivirus software tends to view our processing engine as malicious software due to its nature and therefore will try to interfere in its actions, thus making the search index unreliable.
2) When Microsoft performs indexing on the drives, the index folder will sometimes become corrupted and therefore lead to incorrect search results. This is typically the behavior when searching seems to work correctly for a while after reindexing and then seemingly breaks again.