First of all:
I tried different browsers and cleared the cache ( server side + browser)
The problem seems to be that the Elementor Header conflicts with the Header from GeneratePress.
I have deleted every single element that would be conflicting with the header.
Site layout is set to Elementor Full Width (on all pages)
I have a custom element to prep all sites with the same Layout (just removes sidesbars, deactivates featured image and title).
The curious thing is that I have two navigations on mobile. I can deactivate the non elementor one by disabling the header in the previously mentioned Site Layout element. That doesn’t solve the issue either.
If I create an element to merge the headers, the elementor navigation works. But I only want it to be stickied to the top, not merged.
I’ve been digging through all settings multiple times, but I hope I missed out one so it’s an easy fix.