It actually already does that already, and that's what is causing the problem i think.
The problem is mainly the free classics dlc, this was converted from fpsc assets by volunteers before pbr was introduced, back then if you missed out the shader line it defaulted to entity_basic.fx and worked fine so they just left them out.
But what i think is happening now is with pbr being introduced the default is now apbr_basic.fx so its automatically applying the wrong shader which is why you're seeing issues.
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