I'm getting mad at realizing how the material instances are assigned in Blender. Coming from Max, it's driving me crazy to not understand WHERE the material library for the scene is. I am branching here and there but without really a clue WHERE the material library is, and I can't have a concrete output with my materials, it doesn't work as I expect to. Is there any decent tutorial to understand how to manage the materials in the scene and assign them to objects like instances instead than like copies and copies and copies of the same material?
Just to conclude: I am writing this question because I have an object that, no matter what, it doesn't want to show me one material. I tried to move up and down the materials in the material panel, change it, etc.: no way. And I don't know why.
Here is a video: https://photos.app.goo.gl/1T4hJL3fb2J6JgHz9 What am I doing wrong?