My Storyline Screen Casts are capturing part of my second monitor

I use double monitors. When I record screen casts using Storyline 3 it records part of my second monitor screen even though the red box is only on the first screen. My settings are 540 X 720. I have set Win 10 Project settings to "Duplicate" (shows everything on each screen - does not extend). I have tried to adjust the red box so it doesn't reach as far, but it still shows the other screen, only now I see the red line. I tried cropping the video in Storyline, but received the message "The video could not be encoded." I tried turning off my 2nd monitor, but somehow it still recorded part of the second screen area as black space.  

Is there a way to change the orientation of the recorded area to portrait? Or are there other settings?  

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