While Qlik visualizations have an "Include zero values" checkbox at the global level in the add-ons property section, this doesn't work well on combo charts with multiple measures, where one measure might evaluate to 0, but the others might not. Instead, if I want to hide a null data point, which equates to 0 when aggregated, I have to write some tedious code like:
if (sum(x)>0,sum(x))
It would be far more simple to include a "Include zero values"/include nulls option for each measure.