No Alpha Channel In Cubemap RenderTexture..? Unity Seems To Overwrite Alpha..

This has been very frustrating for me. I am attempting to render the scenes depth into the alpha channel in a cubemap, but Unity seems to override it with a weird alpha image. The image appears to be black for sky, and white for any surface... I have used this technique on regular render textures many times using 'keepalpha' in whatever shader I am using. This has been very frustrating cause there seems to be no answer for this anywhere on the internet. Please, if anyone knows a solution to stopping Unity from overwriting the alpha in real time cubemaps, please let me know.

 

Anyone from Unity answer this question?