Scene Capture 2D on mobile - wrong Alpha


Looking for some help on a little issue that has been troubling me for a little while now…

I have to render my character separately using a SceneCapture2D in order to use that output texture in a UI widget.
Everything looks fine on PC but when I preview or build on mobile the result is very different. Basically, the Alpha channel form the SceneCapture2D don’t match the RGB channels, in short what’s in the captured scene (see image below)

As you can see, my model is an egg like shape while for some unknown reasons my alpha has 2 rectangles.

On my SceneCapture2D component, I use the [Use ShowOnly List] as Render Mode and [SceneColor (HDR) in RGB, Inv Opacity in A] as Capture Source settings.

Any idea what could be the cause?