It appears that there is currently a bug with Material Function Instances where the Landscape Material that is referencing/using multiple instances of a material function does not seem to use the actual instance of the material function but the base/root material function.
The issue came up when i started to apply different textures into different instances of the same material function resulting in only the textures showing up on the landscape that were used in the original material function.
To replicate this bug you can take a look also at into the the free marketplace asset “Grass Landscape Material Vol. 1” and try to paint anything on the landscape than the first layer (which will simply not work as all layers appear to be painting the same layer).
Alternatively create material functions from the starter asset materials and try to paint instance.
This bug appears to affect all landscape materials that use material functions containing textures.
We’ve made a switch to a new bug reporting method using a more structured form. Please visit the link below for more details and report the issue using the new Bug Submission Form. Feel free to continue to use this thread for community discussion around the issue.
Is there any update on this? The company I am working for switched their project from 4.25.4 to 4.26.0 and now all the landscape material layers (material functions) show the same basic material from the first layer. The layer information still seems to have all vertex data but the layer-node does not use the proper materials on it. This is a serious issue.
Moving all the internals of the old (4.25) base Material Function into a Material Layer and then using that material layer fixes this. It some work to convert everything, but at least it fixes things.