[Browser Viewer] Current Section disappearing from Header/Footer

I set the Browser Viewer (Android Chrome) to show Current Section on Header/Footer, and it often disappears from first chapter.

When the chapter is loaded, it shows. But for a few Calibre pages (the number of pages vary each time I test) , it disappears. This phenomenon is on first chapter only and in all books, it seems to me.

I don't know if it's a bug or my phone or my system is wrong. So I wonder if anyone happens to see the same thing?