Cache Studio - Find in Files does not work, returns nothing

• select target namespace (e.g. SAMPLES)
• Find in files 
• Find What:   (e.g. person)
• file type (e.g. *.cls )
• uncheck all boxes
• forget all filters
• eventually check  Search in System Items
• (Match case is a source of surprises )
• (Match whole word only is fair chance to see nothing)
• FIND and be patient to see the full result

Check if Output Frame is open.
IF it resists to appear.

• goto fullscreen mode
• click to View / Output  (ALT+2)

If still invisible:

• move the mouse pointer slowly up from the down border to catch the top border of the output frame
• pull it up to make is visible.