Polylang string translations dos not saving

Newbie with WP.

Theme: customizr installed and working with a child theme.
Plugin Polylang installed following this instructions: http://themesandco.com/snippet/using-polylang-customizr-wordpress-theme/

Problem:
String translations is not working.
I can write a translation, but it is not saved.

If necessary I can give someone access to the site...

proquint.com

Thanks!
Helena

ps: I have already asked for information , see here:
https://wordpress.org/support/topic/strings-not-being-saved?replies=12#post-6525925
but it still doesnot work.

Maybe if someone can come and check the backend...