PNGs do not have transparency

[imagitama]

I am using MovieRecorder with output PNG:

My camera has a background of alpha 0 and has a render texture with transparency (RGBA32).

When I use a script to encode my 2D texture as PNG it saves with transparency. When I use FrameCapturer it does not save with transparency.

I set the capture target to both Frame Buffer and Render Texture and no difference.

Is there something I am missing? Could this be changed?