Sketchboard usage has been updated. Trackpad scrolling now moves board around and zooming can be achieved by pincing on trackpad or pressing Cmd key while scrolling.
When you are using mouse you will need to press right mouse key when moving board around.
You can still change the default behaviour to legacy usage from the menu.
Menu > Settings > Mouse and Trackpad Usage
Troubleshooting
In case horizontal scrolling initiates browser’s back navigation guesture. Please restart the browser or close all Sketchboard related tabs.