The version of Epiphany which has to ship with Ubuntu (because Ubuntu is only shipping GTK 3.18) is pretty outdated [1]. I have been trying to move away from Chrome to Epiphany slowly but was encountering quite a few issues which I reported to GNOME and they were like "Oh yeah, we fixed this a long time ago, get the latest version".
I got the latest version via flatpak and I've completely replaced Chrome. There are still a few issues to be ironed out in flatpak (like notifications and downloads support), but it's getting there!
[1] https://blogs.gnome.org/mcatanzaro/2016/03/30/positive-progr...