I know this is a bit late....
The sine wave you are seeing is PURPLE, yes?
Scroll down to the PURPLE menu on right side of screen. (Using up or down arrow buttons).
— It's the one that says "Ex".
Click "OK" button.
Using the up or down arrow buttons, highlight "Ext Refn".
Click the right or left arrow buttons until there is no image on the screen.
That wave is an example of a reference image. I believe you can load your own reference images in as well.