Bug Report: AE CC 2020 Premultiplied Alphachannel from ProRes 4444 will result in black outlines
When using ProRes 444+ with premultiplied Alpha in AE2020 (17.x) on MacOS 10.14. and 10.15. the key will have black outlines. Bug wont occur in AE2019 (16.x) or with AE2020 on MacOS 10.13. Please fix this issue.

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hildegard hildegard commented
Not fixed in 2021
Workaround usind channel combiner not a long term solution -
Lucas Baade commented
The interpretation of the background color has no effect.
Rendered a premultiplied transparency clip against a red (255,0,0) background.
There is no chance to clean the footage from red. -
Sen Haerens commented
Still happening on Windows 10 with AE 17.7.0. No issue in AE 16.
Incredible that no one notices this bug... -
Creative Studio commented
This in an incredible unaccetable issue.
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Antoine Autokroma.com (Independent Developer of AfterCodecs, BRAW Studio, PlumePack, Influx) commented
Is the issue at export or at import ? You can try AfterCodecs ProRes 4444 profiles with premultiplied alpha and tell me if it has issues https://www.autokroma.com/AfterCodecs
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Marko Milankovic commented
As well, windows 10. Premultiplied Alpha not working is unacceptable. It is very important feature. Please fix it.
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Joseph Lawson commented
This also happens on Windows 10 as well for me. It's very disruptive to an otherwise clean workflow. I'm glad I'm not the only one, and Ihope this gets fixed soon.
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Daniel Fallik commented
Simply terrible! This needs to be fixed, it works well in Premiere on latest version.