Alpha not preserved on DXV clips in Advanced output?

[thedarkroom]

Hi,
I'm mapping onto a set with foreground and background shapes. So I'm splitting the input clip to the foreground [at top of frame], and background [at bottom]. In order for them to sit over each other nicely I need to use an alpha channel in the clip, with DXV. Now.. in the Output Transformation window [in Advanced output] the alpha channel is active, but on my output screens it's not. Wondering if this is a bug, or if I'm missing something.
Thanks.

[Joris]

This is indeed a bug, thanks for the find!