The problem is the following calendly script which I really need as it pops up a calendar (without this script your header remains sticky after the first section, but the calendar doesn’t pop anymore)
Is the script removed right now? Everything seems to be working.
It’s strange that the nav would work only up until a specific point. It’s possible that there’s some javascript in the calendly files that is conflicting with the sticky nav. Not sure if I could pinpoint the exact issue as I don’t see any errors.