Yes, we have seen similar issues has been reported by the customer. You need confirm on which portal you are executing the search.
1) If you are performing the search in designer studio then you can try below resolution.
Resolution --> Reindex the rules and try executing the serach . Steps for the same : Designer Studio -> System -> Settings ->Search and reindex the rules
2) If you are performing the search in case manager portal then you can try below resolution.
Resolution --> You need to verify the value of 'pzWorkLastUpdated' set in Activity "CPMSetSearchWorkParams" (which gets called from Activity "CPMSearchResultsWork"). You can private edit that activity and change its value to 'Updated Anytime'. Perform the search now and see it is working or not .Refer the screen shot attached for the other values applicable.
Are you referring to searching of cases in designer studio or case manager portal.
Please confirm if indexing is properly done. You can traverse to this page via Designer Studio -> System -> Settings ->Search and reindex the rules. Perform search once reindexing is completed and let us know if you still facing issues.