Maxwell Render | Official public forum

Its just because the MAX plugin doesn't has such a feature (I assume you're using the max plugin, otherwise just ignore "MAX" and replace with your app. )
This will not affect the rendering at all, and Imo its just a matter of time till NL will implement this feature, because it would be useful to have such a feedback.

But I think it would be nice to have an approximation of the shaders inside the material edittor. For exmaple, you could see how glossy a shader with a UV roughness of 0,4 would be, or how does your freshly applied glossyness map affects the look of the highlights witout the need of a testrender, because when it comes to testrender maps, maxwell is a real pain, especially when trying to preview the effect reflection/refraction related textures.

Well, for now, I give a clearly recognizable name to my every shader, and use the Material/Map browser to navigate through my shaders. Its not that pain at all, you just need to get used to a different approach.

But whats really annoying me, is that all the metal and glass shaders appear totally black in the VP, makes a lot of my scenes a real nightmare to manage in shaded mode. Also, I dont know from my VP, where the highlights will be, to get some idea, I need to fiddle with adittional shaders and light sources.

Yeap i can agree a material preview would be nice to have especially if you're new to Maxwell, but in all honesty i doubt it's a prioritized feature. I rather see them tweaking and optimizing the main core of the engine than adding such a feature. We all benefit much more from a solid stable and fast core

But they most likely implement that into the plugins just in time for the final release, that's very likely to happen

/ Max