When I used an Ubuntu server for my Ansible Node I experienced the same issue. Once I did some troubleshooting I found that I was running an older version of Ansible. Check to see what version you are running. I used the following article to upgrade to a newer version and that resolved the issue: https://www.cyberciti.biz/faq/how-to-install-and-configure-latest-version-of-ansible-on-ubuntu-linux/ .

Hope this helps.