Hi Ander,
We had taken a look at your website’s HTML source code.
Forside
The HTML and javascript code for responsive menu pro is in the webpage.
This is most likely to be a plugin conflict.
Please add responsive menu pro shortcode in the page content ( using WordPress editor ) instead of in a third party plugin’s option. If it still does not work, then please clear cache and check for plugin conflict.
To check for plugin conflict. Disable all of the plugins at once and enable them one by one by checking which one is causing the conflict.
Regards,
Kriti