Chroma Key Alpha issue (Linux only!)

[magdesign]

Adding a ChromaKey after a Roto function seems to break the Alpha behaviour.
Works on Win10, but does not work on Linux!

fig.1 Expected behavior:

fig.2 Actual behavior:

We tested the comp on a Linux and a Windows machine.
It worked as expected on a Windows machine!

Steps to Reproduce

Open this scene (first rename to Alpha_issue.ntp)
Alpha_issue.log
Get the used image file (rename to image.png)
image.log

Check if it looks like on fig.1 or fig.2
Check on a Linux and on a Windows computer to see the different results.

Versions

Natron RB-2.3 at version 426db22
Ubuntu 18.04 LTS

[magdesign]

When using the ChromaKey only on footage with an Alpha channel, the keyer turns the alpha channel to black.
Looks like an issue by ChromaKey.

[magdesign]

Not an issue, is a missusage of the tools... will post a tutorial for this....

sorry for filling in an issue.