Sadly in frustration I ended up fudging it and using a sky sphere just like what was suggested above. But it was a clunky solution, would be great if there was a solution that actually involved keeping the sky and not covering it up with a sphere. Also had a similar problem on another project using the sky generator and a mirror. Every reflected fine in the mirror except the sky, it was black. Not sure if it’s related to the water problem but ended up using the sky sphere again as a quick fix.