Press and hold on the x on the top right of notifications does not work? (on iPhone it is done via 3d touch)

On my iPad pro, the X button only clears one days worth, so if I ignored them for a few days, I have to clear each day separately. Usually not a big deal since I do it every few days, but sometimes it can add up.

Idk about the iPad Pro but on iPhones with no 3D Touch there simply is no way to clear all notifications on iOS 11