The default version of Arachni that comes with Kali is a bit outdated. There is a newer version (2.0) that has never been released officially but that is available for download here: http://downloads.arachni-scanner.com/nightlies/

This version corrects some bugs with newer technologies such as AngularJS and single-page apps in general. I personally prefer to install it via the "nightly builds" link provided, but there is also a GitHub with an experimental branch available here: https://github.com/Arachni/arachni/tree/experimental . There are some rubygem dependencies issues though, and the nightly build comes pre-packaged with all of them.