Need some help with display timings/blanking intervals to move a tear off-screen

[GoldenOne]

Heyo!

I am in need of some help regarding monitor timings/blanking intervals.

Specifically, how to move the blanking interval. Because right now instead of the frame starting at the top/bottom of the vertical area, its starting/ending in the middle. Resulting in an image like this:

https://thegoldenone.co.uk/0587979320.png

My current issue is this: I have a display, and a capture card, cloned together with the display at 120hz and the capture card at 60hz.
Settings are as shown:

Monitor: https://thegoldenone.co.uk/0469930223.png
Capture Card: https://thegoldenone.co.uk/8418084220.png

The timings are synced perfectly, which means I'm getting a perfectly smooth video to both the display and capture card, BUT, on the capture card, I have a stationary tear in the centre of the screen, as shown here:

https://clips.twitch.tv/AwkwardDelightfulPeanutYouDontSay

If the timings were out, then the tear would be moving.

So I think i'm close to getting this working perfectly.
Does anyone know, what should I change/adjust in order to move this tear off screen into the "porch" or "sync" area? (I have limited understanding of this but this document explained it quite well http://www.analogway.com/files/uploads/white-papers/wp-custom-formats-082714(8).pdf )

If anyone can help me out with this that would be awesome.

Additional info:

Monitor: Acer x34p @120hz (gsync disabled)
Capture Card: Elgato 4k60 pro
GPU: Nvidia 1080ti

Monitor is running over displayport
Capture card is running over HDMI 2.0