Gantt Chart Cuts Off in Dashboard View

I created a Gantt chart widget in a dashboard that pulls data from a report that in turn pulls that data from a sheet. The dashboard Gantt allows me to scroll both vertically and horizontally. All my rows can be seen with the list of tasks, but the columns that are supposed to show the full timeline cut off part way through the timeline. How can I have the Gantt scroll across the entire timeline?