Two finger swipe not working well with Magic Trackpad

Two finger swipe is not working well with Magic Trackpad

It barely works - sometimes I'm lucky and with a dramatic swipe I can move between Safari pages.

If I do it 'normally' the page moves, but only slightly.

I've got it selected in Accessibility, and it used to work.

All other 1, 2, 3 and 4 finger gestures work fine.

All software is up to date, 10.13 (17A365).

Anybody else have the same issue?