Hi @LeXXik,
Not sure why it isn’t working in Orthographic camera mode but in general Element entities under a 2D screen have a special shader pipeline used. Using a new pc.Shader here most likely breaks the program that gets generated internally by the Playcanvas engine and allows you to render the Element as part of a 2D screen in the UI Layer.
I’d say that you are better off exploring the Playcanvas shader chunks as a starting point in writing custom shaders. It’s very powerful and allows you to write shaders that take advantage of many features the standard Playcanvas materials provide: text effects, fonts (and more for non Element entities like PBR lighting, shadowing, tonemapping etc).