Github actions checkout missing files .gitattributes export-ignore

Currently I am implementing Github Actions in a project. My workflow file contains a actions/checkout@v2 step as I need the files of the current branch.

Unfortunately this checkout step does not include files that have been defined as export-ignore in the .gitattributes file.

It looks like other repositories are doing the exact same thing without any issues.

Not sure what I am doing wrong. Anybody has any experience with this or had the same issues?

Github links:

For unkown reasons it works again without any changes.