I believe the issue here is caused by what Apple calls “content change”. Something on the screen changes (a navigation comes into view, for example), the iOS + Chrome combination requires a double click.
A way to test this is to:
1. Keep the Mobile Header turned on
2. Enable sticky on the Mobile Header
3. Turn off the “Hide when scrolling down” option
This should make it so the Mobile Header is always visible – nothing changes on scroll. Does the double-click issue go away?
Obviously, this is something we need to research further. To me, it seems like a Chrome/iOS bug, but we may need to find a workaround.