[נפתר] Change custom post type slug

I am using WPML to make the site bilingual. I am using a third party plugin to create Custpm post types (CPT), and now I would like to change the slug name of the CPT. The CPT is set to be translatable, is there a safe way to change the slug name of a custom post type?
When I tried changing the post type slug name, all the existing posts are lost, so I have to revert it to the old slug name to get the posts back.

Solution: WPML will allow you to translate the slug in the second language. WPML won't change the slug in the original language. So if you want to change the original, you should change it, resave permalinks, and then translate in the second language.