gh-pages branch remains empty after push to master; pages build and deployment not triggered

Hello. If I understand correctly (correct me if I don´t please), if I commit to master I should expect two actions to be triggered, the custom one from the yml file and the pages build and deployment from github itself right? I have created the yml workflow file under .github/workflows/, set up the deployment to be from gh-pages branch but when I commit to master, gh-pages remains empty so I get a 404 when I go to my pages url

This is how the repo pages section is configured:

Thanks in advance