The Anko plugin was working before, but after the update of the Layout Editor it broke.
But I must say that I don’t have any real issues with designing layouts. I never used the Layout Editor myself, when building my layouts. In the case I need to build a complex layout, I do so in xml with the preview and manually convert it to Anko. That takes me an additional 5 minutes. Which is 1% compared to the effort I do my UI fluent and my app responsive. (If an update of the Anko Plugin is released converting could also be done by the plugin.)