SSRS Rectangle visibility based on Parameter Value
Check out this answer. Basically, you want to combine all the values in your selected list using Join then use InStr to detect if the value in question is there.

So if you have Rectangle Rec1 which relies on param option "Rec1Visible" in parameter RecVisibility being selected, then an expression like this should work (pseudo names) for Rec1's visibility property:

=IIF(InStr(JOIN(Parameters!RecVisibility.Value,","),"Rec1Visible")&gt;0,true,false)


Use the same code for each visibility expression, with the relevant value, to control the visibility of your rectangles.