Importing ground materials (markings) not working anymore

Hello guys, whenever I try to import any material, it works fine. But when I do build the project, the textures all of a sudden become broken and not saved anymore, and the game just CTD.

This is the error i get
apparently i set something wrong in the folder files even though i followed the tutorials
PackageSources\MaterialLibs\lirz-materialLib\texture

Plus, I see a red error message on the material inspector saying “Material is not from Selected Asset Group and can’t be changed”.

Anyone have an idea about this? I’ve spent all the last week looking to solve it.