I basically have the same problem described here: https://theme.co/apex/forums/topic/fixed-navigation-covering-section-headers/
When I click on one of the anchor links in the menu, the top part of the section the link refers to is covered. I have one-page navigation enabled, but it doesn’t seem to make a difference. I don’t hava the problem when using the footer menu.
The site is https://grgipfel.org/
Any help would be much appreciated!