FWIW it doesn't work on Firefox 52.9.1 ESR on Windows XP either, but that isn't now a supported browser of course.
I would report it on GitHub, it's more likely that @Emdek
will pick it up there I would have thought.
Done. :up: Following your suggestion, I've opened a new GitHub issue (#1695) (https://github.com/OtterBrowser/otter-browser/issues/1695).