Broken underwater textures, no leak

In the Hammer Editor, after I finally fixed a different issue involving "Solid Water", my water is now (mostly) working properly, with an animated surface and proper water physics.

The problem lies in what happens underwater. While above surface, none of the underwater textures show:

I am happy to lower the water brush down so the sides are not visible from above if need be.

While underwater, 3 of the side textures show. However, a large glass one that looks into a sealed box does not:

This is happening in another water body as well. I am confident the map doesn't have leaks because the water textures actually work and the compile time has increased by a lot – and the fact that I have completely sealed my skybox.

So, basically, what is causing this issue?

And as a side (but not major) question, how do I change my water to make it, say, more white and visible underwater?

EDIT #1: What I am going to try (I have made it, but not had time to compile it and test it) is making the glass observation wall hollow, then using the structure below

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Where the solid lines are textures (glass) and the dotted ones are Nodraw. This means that only 1 layer of glass is visible (not that the opacity of the glass was the problem). I will post my results when I have tested it.

EDIT #2: Absolutely no better, there is no change. Right now I am testing it with a different texture, but I'm not sure if this will make a difference.