Reflection capture - black areas relative to camera?

This is the reflection view:

Looking down


Looking up

It seems this is related to the black area being outside the range of the reflection capture. Adding more reflection captures doesn’t increase the accuracy or remove the black area. Adding a huge reflection capture (box) to cover the whole map hasn’t fixed the black areas either. (even after building reflection captures)

I’m not even sure the black area is what is actually causing issues within my reflections though, I was expecting to see my normal map used to affect reflections, it seems like it isn’t being used for the water material (which is currently just opaque anyway).

Part of my issue is also the Detail Lighting result on the material. Not sure what is causing this checkering - but it’s part of the light pass.

Has anyone experienced this before/have some decent solutions? it’s probably a setting or something similarly simple I’m not aware about that’s causing both behaviors.