Use zn([Revenue]) as a calculated field and bring that to the view, it should go in place of the current revenue field. The zn function turns nulls into 0s.
Alternatively, check if you special values are displaying:
Then your nulls should appear on the bottom right of the chart:
Click on it and show data at default position:
to your numeric field put this zn (metric) to show the 0
Thanks for detailed response Mavis.
For some reason it did not work for me until I changed from continuous to discrete.