On this site https://www.chagim.org.il I have a collapsing header when scrolling.
It works with a box in the header as you can see here
The code for it is very simple and is in the SITE tab
It worked fine for several months. Now it works just in preview mode, but not on any browser, even after clearing cached images or using incognito mode.
Moreover, there is a white space between the header and the page
You can't see this space in the editor, as you can tell from the first screenshot.
As it's all fine in the editor, I believe it's a bug in some deeper layer of the system.