@slugify-title does not work properly

I've tried to use [this recipe](https://learn.getgrav.org/cookbook/admin-recipes#add-a-custom-page-creation-modal) to create custom modal.

When I create new page with cyrillic title, @slugify-title does not work and new page can't create.

Slug rules in blueprints do not give any effect

I've also tried to use [widget plugin](https://github.com/sojimaxi/grav-plugin-widget) with same functionality but it also doesn't work. Grav creates page only with single dash