Indeed, the Rain and Water options were greyed out as I did have the previous rain fix and a custom water shader. However, when I restored the original rain and water files and then selected them in the Fixer tool config I didn't see the rain and water files get updated/replaced in the ShadersHLSL folder. So, now I'm pondering if I'm using stock files or not (though I don't have the umbrella effect), so perhaps not.