I have a setup where I put different colors in different space pipe levels, when mix them as needed near the painting.
The levels are forced using flow gate and a constant signal with an intended color. It allows to use the same blueprint for all color patches.
The previews work on space pipes, but break on mixing.
If I replace the flow gates with normal pipes, so that the setup is functionally exactly the same, the previews work everywhere
Please check this save game: drive google com/file/d/1hnc3dNzL7Bc-8a4nvTFif6byH455xUSP/view?usp=sharing
It's an empty newgame demonstrating the issue in a simplified setup.
There are 2 markers: at one location there are previews, at another - there's no.
The only difference is in the miner platforms.
It seems that the issue is the disabled flow gates. If I add just one of them back, the previews disappear.
It appears that the preview logic seems to be treating flow gates as pipes and because of that it thinks that all the layers may contain all the colors and mixing preview is broken completely because of that.
The refined implementation should pay attention to constant signals on flow gates more carefully. If the color before the gate is known, the logic should be applied and propagation shouldn't happen if the flow gate will be closed for this color.