Hi @Stijn,
You can avoid such behavior by defining a new JavaScript calculated custom field - Current Priority. Please see an example with a similar problem with the Assignee dimension here - Calculated Measure shows issues that have moved issue types.
Also, if you are looking for the number of days issues spent in a particular status, use the Transition Status dimension. Otherwise, in the current report configuration, the Status dimension in report columns limits the result from issues currently in the “Triage” status. Please see more details on issue change history measures and dimensions here - Import issue change history.
Best,
Roberts // support@eazybi.com