When using render.enable_texture and you render a model that use the rendered texture you will only get black if the model material contains a sampler in the texture unit you are using for the render target.
Expected result:
The sampler settings from the render target should be overridden with the ones in the sampler. Or atleast it should ignore the settings in the sampler and don’t give out black.
(also, since you can’t set the index of the model textures or the samplers in the material you can really only have the rendered texture as the last sampler in the material. This makes it harder to have many different shaders with different number of static textures use the same render target)