Using action to create 'master' branch fails

[MClauwaert]

We've recently started using this action into some of our workflows. It's been working great. But in one of our repositories, it consistently fails when asking the action to create a branch "master".

Is there any way to get some additional information on why it fails?

We've also tried the identical action on a test-repo. There it does work.

There's no branch protection rules or other special configuration associated with the failing "master" branch.

Edit:
Also double checked the commit SHA begin used. It's the correct one.

Edit2:
Using the Github REST API via Postman does allow the 'master' branch to be created.