Recent items in a search report

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Could someone help me in understanding the persistence of results under Recent <items> section in a search report?

Taking a scenario where a staff account uses the same machine to access a service cloud instance, once he makes a search request and select an item, it would them be available under Recent <items> section when the user

1. Close the current record, open a new record and open search report

2. Restart service cloud, open a new record and open search report

3. Restart computer, open service cloud, open a new record and open search report

I have tested this behavior on multiple machines and found that the option 3 is not consistent (i.e. few users are unable to see recent items in search report once they restart their computer.