The Ubuntu SDK IDE and many of its tools are not supported at the moment. While the lxd issues might be fixable, you will run into more problems down the road.
If you're looking to create applications for Ubuntu Touch, the recommended tool is clickable, a simple but powerful and easy-to-use CLI tool. Clickable can build and package Ubuntu Touch applications, and you can choose to install them on a connected Ubuntu Touch device or run them directly on your desktop.
To install clickable on Ubuntu:
Add the PPA to your system.
sudo add-apt-repository ppa:bhdouglass/clickable
Update your package lists.
sudo apt-get update
Install clickable.
sudo apt-get install clickable
Configure docker for clickable.
clickable setup-docker
If you already have a project set up and ready to go, just run clickable
in the root of the project. If not, read this for information on how to get started.
If you really really want to use the SDK, you might want to check out the virtual machine download in this Ubuntu Touch programming course, but I recommend using clickable.
If you don't care about Ubuntu Touch, just use QtCreator, which the Ubuntu SDK was based on.