There’s a complex mix of transmission, alpha blending (.transparent = true), and opaque materials here, which you probably don’t want. Note that transmission only shows opaque surfaces behind it. Transmissive and transparent surfaces are not visible behind a transmissive surface.
Also – it’s usually best to have .transparent = false on your transmissive materials, to keep metalness at 0, and to decrease roughness instead if you prefer crisper reflections.