My solution and it seem to work fine, I created a new folder in my child theme, named it wp_knowledgebase and added the css file manually and that seem to work well.
Try it and see if it fixes your issue. I also added all the files:
taxonomy-kbe_taxonomy.php
taxonomy-kbe_tags.php
single-kbe_knowledgebase.php
kbe_style.css
kbe_search.php
kbe_knowledgebase.php
kbe_comments.php
archive-kbe_knowledgebase.php
