So I've been investigating view models as an alternative to first person weapon sprites. I've found a workflow from Blender -> GZDoom that works, and everything looks good. Except for one little problem...

(Pictured: A dark room, a very bright gun)
It appears as though view models are rendered full bright, except when they aren't:

(Slightly better!)
World models render just fine:

I thought I was doing something wrong. However, this issue also appears in other mods with 3D view models, such as the Extra Heroes mod for Samsara:

(Quake 2 edition)
I cannot tell if this is user error, an actual bug, or a limitation of the engine. I am using a few visual mods, such as NightFright's Brightmaps mod, but none of the effected models have brightmaps associated with their textures, nor do their frames have BRIGHT attached to them. I also understand that GZDoom handles view models and HUD sprites differently than "world" objects. However, this doesn't seem like intended behavior.
I'm posting this here, since it is an asset issue, and I'm curious if anyone else knows of a solution to this. I'm including a slimmed down version of a model test mod I've been working on to sort out my workflow: modeltest2.pk3