Thanks for the fast help and information!
For anyone else encountering this problem on a multisite setting.
- Install KB but keep it deactivated network-wide or deactivate KB network-wide if already installed.
- Only then create sub sites
- Activate KB on each sub site individually
Please adhere religiously to the order above, because if you had KB activated network-wide before creating a sub site, the plugin configuration will not work on the sub-site!