Lost parameter label highlighting Follow

I was messing around with ReSharper performance improvement settings and somehow managed to turn off the automatic highlighting of parameter labels in method calls.

Example: in something like CallSomeMethod( aVal, argName: anotherVal) the 'argName' is displayed in exactly the same color and font as 'anotherVal'. It used to be in a different font/color.

How do I re-enable the formatting? I couldn't do it through the performance improvement screen. I suspect I need to re-enable something inside VS Options...but I don't know where to look.