Why render target stop rendering Alpha in 4.12?


We started creating project on 4.10, then swapped to 4.12 for betcher optimization in VR and some other features.

For subtitles in VR I’ve created system using render scene capture ( using alpha from render targget to mask black BG ) and widget 3D to create texture with I project on Material Bilbord Component. ( using alpha from render targget to mask black BG )

After swaping to 4.12 render targets stop giving alpha… It’s not a big deal in material, I can create opacity mask in material.
But I wanted to swap rendering method to newly added StereoLayer, and there problem starts. It accepts only textures so I can’t opacity mask for it.

Is thare any way to reenable alpha in render target?

Ok, got some progress, but not in right way…
I set scene capture to render only widget and now instead of full black alpha i got black text and white BG.
Now lets find out if can I invert this process.