I cant add FAQs in category. PLease help

I am using HTML5 responsive FAQs plugin for WP.
When i try to add FAQs to their category, the category keeps empty.
If i add posts to category it works fine but not with FAQs
do you know whats the issue? the owner of the plugin said its a wp issue

Thread moved.

Did you try to enable debug and check the error when you submit to the category?