@ben551445,
The z value in a bubble chart sets the size of the bubble, which is used for visualizing the difference in value between the dataPoints. The size of the bubble depends on the relative difference in the z value of dataPoints, which depends on multiple factors like the minimum z value, the maximum z value, etc.
In your case, having a dummy datapoint with a minimum z value of 0 should work. Please check this updated JSFiddle for a working example.
—
Thangaraj Raman
Team CanvasJS