An additive blend mode won’t do it. Set the blend mode to Normal instead. 

It should work with additive, as it's adding to the output of the Unreal compound which is mostly black, not to the background you're seeing of the office.

It isn't working in any other blend mode though, I also tried with normal but it's not working as I figured it would in any of them.

If the background in the UE5 and Aximmetry scenes are black and the Add blend mode works, I don’t understand what the problem is? To get opaque, non transparent AR objects from the Aximmetry render you shouldn’t have any background in that render and use the Normal blend mode. Add blend mode will mathematically add the foreground pixels to the background pixels and will only work if the background is black. 

Hi,

The problem is that you try to blend this picture before the background (real world) is added to the rendered image from Unreal. When Aximmetry adds the background (video input) then it uses an additional rendered video to cut the Unreal render into the background. And this additionally rendered video (alpha) does not contain your 3D bars.

You should actually blend the 3D bars rendered by Aximmetry to the output of the ARCam_Unreal compound. And use Normal Blending mode:

Otherwise, multiple other settings of the ARCam_Unreal compound may affect your 3D bars in the wrong way.

You can use the following Transmit module tunnels to render the 3D bars from the perspective of your camera:

More on transmit modules here: https://aximmetry.com/learn/virtual-production-workflow/preparation-of-the-production-environment-phase-i/scripting-in-aximmetry/flow-editor/pin/#transmit-modules 

I see you turned off the reflection of the bars. However, you could have transparent reflection by setting the reflection plane's shader Transparency to Add and its Color to full black. This way the reflection can be blended over the real world and the Unreal graphics.
More on reflections here: https://aximmetry.com/learn/virtual-production-workflow/preparation-of-the-production-environment-phase-i/obtaining-graphics-and-virtual-assets/creating-content/creating-content-in-aximmetry-se/planar-reflections/

And if you are using Lens Distortion:

Then you probably want to apply that lens distortion to the 3D bars too using the Camera Tracking and Lens Distorter modules:

Warmest regards,