Getting 404 is very common issue for custom post type regarding their single post. But, this can be easily solved by a simple technique.
Please check following steps-
Step 01. Go to WordPress admin panel Settings>Permalinks.
Step 02: Go to bottom of the page and click Save button.
Step 03: Go to any single knowledge base post. You’ll see 404 issue has been fixed and now everything fine.
Note: From version 1.1.7 plugin can automatically handle single post 404 issue.
You can check following video tutorial for more details-
Last Update: September 22, 2017