So I managed to get this working by basically removing all of the non Mac bundled version of Ruby and Jekyll. So:
brew uninstall ruby
Then I followed @michaelbach solution above to update everything and cleanup brew. I then re-installed using the Mac bundled 2.6 instead of the latest 3.0.
I then followed the Mac Jekyll install process with the following:
gem install --user-install bundler jekyll
echo 'export PATH="$HOME/.gem/ruby/2.6.0/bin:$PATH"' >> ~/.zshrc
When I then ran
jekyll s from my Jekyll repository, I got
zsh: command not found: jekyll. So I had to change the install command to the following:
sudo gem install bundler jekyll
That seemed to have worked and I can sun the local server now. HOWEVER Jekyll recommends that global gem installs shouldn’t happen, so I’m not really happy with this solution, but it’s working.
If anyone has a solution for the command not found issue, I’m all ears.