When installing a new ubiquiti USG router device, or when installing a new firmware, the following manual steps will be necessary:
Cloudflare is not supported out-of-the-box, therefore the following blog post and associated gist reveal what is necessary:
curl https://gist.githubusercontent.com/troyfontaine/7e6f93e32621177fc9a94e823adc52b5/raw/fix_ddns.sh | sudo bash