Problem summary
Nuke Write Node shuffles alpha channel into R, G, B channel
Customer reported version
nuke.10.5v1
Customer reported platform
Linux
Steps to reproduce
1) Launch Nuke and create a constant node with the RGB values of .01, 0, 0, then connect a luminance keyer to it.
2) Set your operation to liminance key, and adjust the keyer A and B inputs so that you generate an alpha channel by dragging your A value to .146 and your B value at .364.
3) Create a write node and write out "test.tiff"
RESULT
It will write out a two channel tiff image that will only have a red and green channel despite creating the alpha from the keyer.
Expected behaviour
Nuke should create the Single channel and Alpha channel.
Actual behaviour
Nuke attempts to write out its channels in order so instead of writing out an alpha channel it defaults to the next channel in order;
in this example instead of writing out RA it writes out RG, despite the green channel not existing.