Success message do not display

I have a problem with a green success message box that should display after submitting the form.

When you submit one of the three forms here (on the page made with a custom theme):

https://logsystem.pl/demo

you will receive the green success message box

but when you submit the same form here (exactly the same forms but displayd with the shortcode on the two elementor pages):

https://logsystem.pl/demo-log/

https://logsystem.pl/demo-log-plus/

then it does not show the green success message box but the email is sent.

and it happens to all of the three forms — they are all the same but acting different depends on where they are displayed (a page made with custom theme or a page made with Elementor).

can you help here? maybe I am doing something wrong?

Thank you.

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