This guide will detail what to do when no window seems to appear when you click print for a FOS report.
With FOS open, select Operations.
In the window that shows up, select Report > Run Only (Using previously selected options)
Select any report/report you need, and select Print.
You should notice on the taskbar a blue airplane icon. Hover over it until the window preview appears, then mouse over that, right click, and select Maximize.
This will force that report window to maximize onto your active screen, allowing you to view it.