Webkit-GTK version installed on my system is 1.8.1.
I hope there is a way to fix this issue.
While I don't doubt they've changed quite a bit from when this issue was made, this issue is still present on :
Epiphany version : 3.33.1-2b3776d2
Webkit version : WebKitGTK 2.24.1
Works here in Ephy 3.33.91-12-g0782ce4ef Powered by WebKitGTK 2.25.4