GitHub Pages doesn't recognize website

I’ve created a GitHub page for my account (andre601.github.io) and pushed changes towards the master branch of it.
But when I try to connect to it do I see GitHub Pages’ 404 Page not found error site.
The site does have a valid index.html.

I’ve also configured a custom domain to point towards it, by setting a CNAME file with github.andre601.com in it and creating a CNAME entry in my domain’s DNS setting with the name github that points towards andre601.github.io. But even just directly connecting to the github.io domain does show the 404 error.

The Repository is hosted as andre601.github.io, so GitHub Pages already has it configured as a personal site (Although I personally dislike the fact that it defaults to the master branch without any option to use the gh-pages branch.

And finally does GitHub tell me in the settings that the DNS doesn’t point towards any GitHub Pages server, which isn’t the case.

Additional info
GitHub Repository: https://github.com/Andre601/andre601.github.io
master branch: https://github.com/Andre601/andre601.github.io/tree/master

I use MkDocs to build the site and automatically build it using GitHub Actions. I made this before and never had any complications before. The action worked flawlessly.

It seems to now work for some reason.
Maybe GitHub pages had some stuff cached? Or it just took longer for GitHub to establish a proper connection to the domain?

I now only face issues with the connection not using https, which the domain should have by default (my entire website is having SSL active), but this isn’t an issue of GitHub Pages (I at least hope so).
If someone still would have some tips on how I could solve this would I love to hear it.

Ignore the blurred part. Took just a bit for GitHub to validate a proper HTTPS.