Betcha gone and hit the Fx Bypas Icon.
It's up there on the Video Preview Window's Toolbar. It's the one with the CIRCLE within a SQUARE? What you can see there is the square is kinda cut into 2 halves . . . There are several settings for this:
* Clicked ON for "Fx Bypass" and you get the half that is selected right/left and "ALL"
or
* Clicked OFF and the for "Fx Bypass" and you get the half that is selected right/left and "ALL" is not selected
One of these WILL get you the same result. In any event, Fx Bypass will show you left or right bypassing IF that option IS selected.
There is another option and that is to DIRECTLY draw a USer definable area DIRECTLY onto the Video Preview Window - that's a LEFT drag over the space.
There are other options like selecting that which you have copied to clipboard - neat if you are wanting to do colour correction FROM another event and you want to correct TO or AWAY from that Event.
Click on that Icon! Betcha that's it . . .
Grazie