AME 2019 Not Handling Alpha Channels properly during export
Encountered an issue today on multiple machines running MacOS Mohave and the latest version of Adobe CC 2019. Timeline in premiere has a ProRes4444 file with an alpha channel on top of another footage file. It looks normal in premiere, and even looks correct in the preview window in Media Encoder. However, when rendering, I can see in the render preview window that the alpha channel footage is being rendered as having a black backdrop. This occurs in the rendered file as well.
The settings I was using are a modified form of the standard Vimeo 1080p H.264 preset. Settings changed are:
Render at Maximum Depth: On
Performance: Software Encoding
Bitrate Encoding: VBR 2 Pass
Use Maximum Render Quality: On
After doing some testing, I found that Disabling the Render at Maximum Depth Option fixed the problem. So I have a workaround, but this is definitely a cause for concern. Hopefully this helps!