Scroll up button not visible

If you go to site and there at the Hamburger menu (left-top) take the menu item About me, and, watching the footer, you will see at the right the scroll-up sign, which is configured in the Customizer. But then goto the menu item Why Boudicca and there you will not see that scroll-up sign.
Why not?
(This also happens at the other sections of my multilingual site..)
The page is made with Elementor.

I asked the maker of my theme and he advised:
“There is this error in your console:
elementor is not defined
That is why it doesn’t work, you will need to check this with the Elementor support team.”
So, here I am.

• This topic was modified 7 years, 2 months ago by gunivortus01.
• This topic was modified 7 years, 2 months ago by gunivortus01.
• This topic was modified 7 years, 2 months ago by gunivortus01.
• This topic was modified 7 years, 2 months ago by Jan Dembowski. Reason: Removed unnecessary second link as it's in the form already

The page I need help with: [log in to see the link]