why do my verified defects not show in the burnup totals?

I have burnup charts for my current sprint which show only defects. Defects which are in state resolved appear to show in this total for each day, but when they are then moved to verified, the spent-time figure is subtracted from the chart.
Both resolved and verified states are defined with the same stage group in the defect workflow so what else is the chart using to decide which items are included in the sum? Why would it ignore some states when making the burnup sum? I see the same problem with burndown. charts.
I am using the SCRUM template.