Why didn't search using the Contains option in the legacy CRM Search return the expected search results?

If there’s an issue with the search results when you use the Contains operator, then the search results may not be properly indexed.

To index the records, run the Optimize CRM Search Indexes and Synchronize CRM Search scheduled processes. The Contains operator is only used in the work areas that still use CRM Search. Workspace and Sales in the Redwood User Experience use the newer Adaptive Search, a high-performance search engine which permits you to search using related information.