Microsoft Engineers are investigating reports of an issue in which some customers are experiencing problems with the Outlook Web App (OWA) search feature. Engineers have ruled out indexing as the cause of the issue and have identified that a recent update to the environment has impacted the search functionality in the Outlook Web App (OWA). Engineers are continuing to develop a fix to remediate impact. Once the fix has been developed and tested, it will be deployed across the affected environment.
Workaround: As a workaround, customers can use the search function in Outlook Online mode or can enable 'Conversations' setting in OWA.
