doesn't work on 4.4.2

unable to get it work on 4.4.2 – after accessing page new page with a slug ended with _html I got only “Oops! That page can’t be found.
It looks like nothing was found at this location. Maybe try a search?”

Disabling plugin or removing _html from slug get this page available again.

https://wordpress.org/plugins/add-html-extension-to-specific-pages/