interpret Footage -> Premultiplied not working
My Prores 4444 Footage w Alpha that is premultiplied on Black, only acts normal when I am in Half resolution preview. As soon as I switch to Full Res or Render, the Alpha is treated as Straight/Unmatted.
Interestingly… if I select the interpret footage option "invert Alpha", the Alpha is only inverted when previewed at Full Resolution, not at reduced resolutions.
When I employ the workaround of adding the effect "Remove Color Matting" (Black) myself manualy, I also get very weird halos and artefacts when previawing at half resolution, which are not a side-effect of simply downscaling.
This occurs in CC2020 and CC2021 (not in Beta 18.2)
Footage is included here:https://we.tl/t-UUxC1SQe4S

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I believe this is now fixed in the current After Effects Beta builds. Please download the latest build (you will need to have build 6 or later) and give it a try. Please let me know if this fixes the issue for you.