This caused me some headaches, so I’m putting it here to solve anyone else’s.
It turns out that non-default Shells don’t use the recommended GOPATH setting, so if you’re using Zsh, FISH or others, you’ll need to set GOPATH in /etc/paths (not your .bash_profile). I’d been having trouble installing Go on my Mac (without Homebrew) and also building Hugo from source, so hopefully this will solve these issues also (so I’m not pestering @natefinch to build and send me dev versions).
Unless you either use the global path in /etc/paths or set the $PATH in .zshrc or config.fish the $PATH will self-erase the next time you open up a new terminal window/tab.