Hamburger menu - Slideout Navigation

Hi,
I bought your theme GeneratePress Premium 1.7.8. It's very fast and I'm very happy with the purchase. I have only one small problem with the hamburger menu (slide-out menu) on the main page on desktop.

My website consists only form two pages (the main page and one additional / second page. Clicking the button from the main page I can get to second page). On the main page I have one page menu in the form of hamburger menu.

The problem is that hamburger menu doesn't work on the main page on desktop (it slides-out but when I click on the names of particular sections it doesn't redirect to these sections).

This problem doesn't exist on the second page on desktop. When I click on the names of particular sections it redirects to particular sections on the main page. The hamburger menu works fine on mobile too.

I would like the hamburger menu (slide-out menu) to work both on desktop and mobile.

I tried to fallowed you instructions. My settings are:

1. I activated Slideout Navigation. I went to Customize > Layout > Slideout Navigation > On (and it should work on desktop and mobile).

2. I also used the option: use Slide-out Navigation Only:
a. I created a menu with the desired items and assigned it to Slideout Menu in theme locations.
b. Then I created an empty menu and assigned it to Primary Menu in theme locations.

3. When installing your theme I didn't installed and activated Woocommerce plugin (I didn't do that because I will not sell any products using website). In your support I read that is one case it was important (installing and activating it).

4. I also deactivated Smush and Autoptimize plugins and nothing has changed.

On the main page I have a page hero (full width). In the Site Header I merged it with content. In Navigation location I selected Above header.

Before I decided to Slideout Navigation I created normal menu located in the header and it worked fine.

I would be very grateful for your help. I'm creating this website on my own. Maybe I did something wrong.

Best regards,
Zbigniew