Thanks for this notification. I wrote at the end of the documentation page:
This add-on could be not fully compatible with some other plugins or themes which also replace WordPress core Walker_Nav_Menu_Edit class from wp-admin/includes/class-walker-nav-menu-edit.php file. Read this discussion for more details.
I see that it’s your case. Devis theme uses its own menu walker which replaces as WordPress’s as URE’s one.
about this item (Problem) a lot of contents we have seen in this forum.
can you simply tell us which exactly in which files must be adjusted?
our system: wp 4.8, ure pro 4.36.1, eduma theme
thank you for your support.
If you have active ‘Nav Menu Roles’ plugin and wish to use front-end menu access add-on from User Role Editor Pro instead, deactivate ‘Nav Menu Roles’.
If your theme contains some related code, make a context search at theme files for code which inherit from Walker_Nav_Menu_Edit class and look how you can disable it and do not break a theme functionality.