Just tried and could replicate this by following the readme from the repository (also on a Mac).
I played around a little bit – initially thought it’s an issue in the gulpfile.js, since that is the one looking for the directory. But I thought…that would be odd. Especially since that specific line is in the repository since it was created nearly 2 years ago.
So, I dug a bit more.
3 weeks ago, good-old renovate bot updated dependencies – and pushed gulp from 4.0.2 to 5.0.0:
Now, that included loads of breaking changes:
I tried reverting the renovate bot commit on my local machine and TADAAA – everything builds without issues AND the navigation bar is present. So, that might be an option for you to quickly get what you want (or specifically check out the last commit before the upgrade to gulp 5.0.0)
So…not entirely sure how the Ghost team handles renovate bot breaking things. @RyanF maybe you can have a look? Happy to help out with a PR, but I feel like the breaking changes from gulp are a bit deeper than on theme level, given that the navigation bar also disappears completely