Check if the engine read all your textures as texture and not normals,
material issue related to the color blue is usually a ‘normal map’ type shananigans (since blue is maxed in expected normals)
I also supect this since it could be an overall parametre that apply that malfunction to all projects
Create one (project) without plugin to eliminate that specific possibilité then focus on how your texture import
I assume you didn’t recompile Unreal to make crucial change around how core material work/render,
because if you did so you can uninstall the whole thing and start fresh
I’m also assuming many of those material are unrelated to each other and you didn’t just misswire something in your single master material that would affect all instances.
So check into :
1.your overall engine parameters
2.Any new plugin that could have cause the issue
3.your ‘blued’ material with the higher parenting
4.If a new imported textuer is imported as a normal map.