I am using Firefox on a Samsung Tab S, along with both Talkback and Brailleback. About 50% of the time, after a page has fully loaded, Firefox refuses to respond to quick navigation keys that I press on my braille display's keyboard. For example, H to navigate to the next heading, or G to jump to the next graphic. Unfortunately, I haven't been able to nail down precisely when this happens, as it seems completely random. Navigation sometimes resumes if I close out Firefox from Recent Apps and then launch it again, but not always.
Please let me know if I can provide further information to narrow this down a bit, and I'll be happy to assist.
Sent from Samsung Tab S