I have just installed an OpenNebula all in the same server. Debian 10. OpenNebula 5.12. I installed the bridge br0 manually. Also the packages for kvm and lxc in the same host. I can download a debian buster lxc image in the datastorage, and upload a Windows iso as image, but none of them can be instantiated as a real VM and end in a failure state. What is missing?
For setting up multiple hypervisors on the same node, take a look at this post.