Sine UE4.24, I think, when you are making a material and previewing monochrome values in any node (Add, Multiply, etc…) they are now shown as red=1 and black=0. Do you know why? For me it has no sense as it is much more difficult to notice little color variations on them (and a little confusing).
As I recall, this happens when you plug a float value into an input that takes a vec3/vec4. It converts it and since a float doesn’t need all the channels, it just puts the values into the first channel (red).
And I’m not sure a node with a scalar-restricted input… (They are something like “flexible”). But maybe a Component Mask with only the green channeld checked?
I am assuming whatever shader they are using for the node preview is converting it to a vec3 and only filling the red channel, same as I described above.
Why’d they change this? No idea, maybe it was a bug they never bothered fixing