Blog Posts Element does not save -1

Hi there.

WP Version : 4.7.1
Theme : Candidate
KC Version: 2.6.10

I am working on a website for a client. With that theme (named, Candidate) King Composer is bundled. While creating pages with KC, I am trying to use Blog Post element , it has 1 option to set number of posts,

Items Limit:

Specify number of post that you want to show. Enter -1 to get all team

But when I put -1 , it does not save and after editor is refreshed it is gone , and on front end it only displays 5 posts to that related category I selected.

I tried to check code on plugin code related to this,

/wp-content/plugins/kingcomposer/shortcodes/kc_blog_posts.php

But I was unable to resolve this.

Can you please tell me why this is not working?

Thanks