I figured out that I need to untick the option of "do not add network drive paths to lauch history (they can slow search) under Program Options/Settings/Search Behaviour. I do use networked drives and don't mind waiting a second longer to get the result I am after. This works well but several times now I noticed that the launch history is cut short and only 4 results show. Once I untick this box the results slowly built up again. I can't say for sure that after every reboot of my pc this setting gets lost but it does happen every few days. Is this a bug? 
