Ansible - dynamic inventory feature not working with foreman 1.17

Problem: I configured Ansible according to Foreman :: Plugin Manuals and want to use the dynamic inventory. I placed the foreman-ansible-inventory script at /etc/ansible/hosts. But it gets never executed and therefore the foreman-data is nevver pulled by an Ansible run.
During runtime the invoked command looks like that:

/usr/bin/python2 /usr/bin/ansible-playbook -i /opt/theforeman/tfm/root/usr/share/gems/gems/foreman_ansible_core-2.0.2/bin/ /tmp/foreman-playbook-66a76e56-b7b0-453d-9d7c-53be84bba0a6.yml

Expected outcome: The Ansible run on the remote-execution provider should use/run /etc/ansible/hosts

Foreman and Proxy versions: 1.17.1