Null behavior as zero not working on line chart
I'm trying to take advantage of the null as zero option, but it's not working for me. This red segment is the problem:
Here is the underlying data, filtering only for records in that red series:
And indeed the chart has the right data points, y = 2 for the interval 2018-07-10 to 2018-07-12 and then y = 6 for the date 2019-04-02, which is not grouped together with other dates. But it should not be drawing a line between them.
I have all three fields used in the chart set to Null Behavior = Zero, like this:
Can you advise on what else I might try to get rid of this connected line, which should be zero for the many dates between its 2 and 6 values?