Weird lighting problem?

Hey,
While I was working on my Portal 2 mod, Portal 2: Exhumaos (it’s recently been greenlit), I noticed this lighting problem on one of the models:

I’ve tried putting in an info_lighting, which seemed to turn it from completely black to somewhat very dark, and disabled shadows on both the prop_static safe body and the prop_dynamic safe door. The safe door is parented to a func_rot_button.
It’s also worth mentioning the safe door slowly fades into light as it opens. The safe itself is covered by a func_physbox which is meant to fall down in the mod sequence. I tried removing this and nothing changed.

Here are some in-Hammer screenshots:

Here’s the safe door covered by the physbox and the button: https://gyazo.com/6d9b7990602b630c94504d237288029f
Here’s the safe door with both removed (dosen’t change anything): https://gyazo.com/6d9b7990602b630c94504d237288029f

Any help would be much appreciated!