10 sec delay in Mark read does not mark stories as read

Stories are not marked as read despite having set “mark stories as read on scroll” and “mark stories as read after 10 seconds”. If I change my preferences to “mark stories read immediately”, they are marked when I scroll.

— Vladimir

Arch Linux 5.18.1-arch1-1 x86_64
Firefox 100.0.2 (64-bit)
Unread-Newest, Story view, split style