Also affects Detail and Layout modes.
Pre-requisites: Trackpad settings as attached as three screenshots from Settings.app.
Open a pattern with reasonable number of items (say, a jacket) and zoom to approx 60% (screenshot from Valentina.app).
Press command (⌘) and use two-finger gesture to zoom/pan up down and left to right.
Observe erratic behaviour. It's neither zooming or scrolling.
I suspect some sort of conflict.