Problems with WP_Query & post-type

Some custom page/post types stopped working several weeks ago. I discovered that most of the problems have to do with getting content via WP_Query & post_type
e.g. Flexslider
new WP_Query( array( ‘post_type’ => __(‘flexslider’,’hbthemes’)
-> this didn’t get any content from the database

After changing to new WP_Query( array( ‘post_type’ => __(‘flexslider’) it works.
Same problem happend with the Staff page (see: https://hb-themes.com/forum/all/topic/staff-template-not-working-anymore/)

I just want to undersand, why this happens & how to ensure that with a future update I don’t need to change manually these queries.