Symptoms
Searching for a record with exact number (e.g INC00074567) returns result for some users and not for others. The users have same roles and user criteria.
Release
Jakarta , Kingston , London
Cause
This was caused due to user preference ts.match which was set to false for this particular user while for the entire system this was set to true.
Resolution
Setting this user preference to true / deleting it resolved the issue.
Additional Information
Go through below documentation for user preference used by global text search.