We are using the WordPress custom post type system to store the knowledge base posts. Getting a 404 error message for the single post is a very common issue when you have installed created the first knowledgebase post. From the version 1.2.0 we have included a patch that automatically fix that kind of issue.
Here goes the manual way to solve single post 404 issue. Go to the WordPress Dashboard >> Settings >> Permalink section and click the save button. Now, check your single KB post and I hope issue has been resolved.