Why do some materials not work when assigned in Blueprints?

So I want to be able to change the material on a number of characters in my scene. Frustratingly, the materials I made aren’t working when set to the characters mesh component. However, some other materials DO work. They have practically the same settings (opaque, default lit etc), and reference textures of the same file type. But the ones I need to use don’t work, they just show the gray squares as if the material is broken or compiling.

Any insights?

Ugh. Found it. Had to switch on “Use on Skeletal Mesh” in the material . Does this automatically get switched on when you apply it to a mesh in the editor I wonder?

Yeah, but some of them were switched on in the materials I had just made. I think because I applied them directly to the skeletal mesh to test them (or cloth, as I had a similar problem/solution with that once I figure out this) . So maybe doing that switched it on in those materials, which is why they then worked.

This remains off by default. All of the “Use Cases” are disabled.