Hover is showing previous value

I’ve got a graph successfully displaying stacked values from a mysql table, using the metric of the game-name to segment the data.
The problem come when I have a day with no data for one of the metrics. Instead of showing 0, or not listing it, it displays the previous data point.

this pic shows yesterday’s hover tip, with “asante” having a value of 1.

This one shows today’s hover tip, when “asante” actually has 0 data entries, but the hover is still showing ‘1’.

Is this an intended feature? Can I change it somehow to actually reflect the daily data?

Thank you!