My licence for the UI.X theme has expired, and I'm not going to be renewing it, because the new version of XenForo is currently in Alpha testing, so a large update will be coming eventually. I'm working on putting the default theme back in, but tweaking it to look better than it did. We will loose the custom nodes (the multiple nodes per line), but it will be faster at loading, because the UI.X theme is quite bloated.