HTML Pages appear but JS fails to load

I’m experiencing an issue:

http://yoello.robinduckett.com/_next/static/GY-N_8DndM4Lrvu2rBnMC/pages/_app.js

This file is listed as 404.

The file was supposed to be here: https://robinduckett.github.io/yoello/_next/static/GY-N_8DndM4Lrvu2rBnMC/pages/_app.js but it does not exist here either

The file is visible in the gh-pages branch and my source is set correctly

https://github.com/robinduckett/yoello/blob/gh-pages/_next/static/GY-N_8DndM4Lrvu2rBnMC/pages/_app.js

So I know it definitely should be working

Any help?