I've just learned reports shared with users who are not also shared to the sheet (or sheets) that contain the base data cannot see the reports due to "security issues". This is - in my opinion - a seriously poor design. If Smartsheet can't secure a sheet / report relationship in this manner, what's to say anything can be secure ?! 
We have sheets that contain data on multiple outside parties, which we want to share with those parties discreetly through individualized reports.
This is design choice makes that impossible short of printing the report or exporting it to Excel, which sort of defeats the whole purpose of cloud-based collaboration.