Was working as expected with libwebkit2gtk-4.0-37 2.26.4, updating to 2.27.91 broke it. Tested on Debian with Epiphany 3.34.1 and 3.35.92.
Still a problem with Epiphany 3.36.0 and libwebkit2gtk-4.0-37 2.28.0
I can't reproduce it. It seems to be working for me here when using the touchpad. I don't have a touchscreen to test, though.
After doing a fresh install, the issue has disappeared. Thanks