eazyBI, by default, imports the dates with the server timezone.
You can configure the time zone in the eazyBI data source if you wish to convert the time from the server time zone to some other or specify different working days: Jira Issues Import - eazyBI for Jira.
So the workdays in transition status count all days except the configured weekend days, by default based on the Jira server timezone settings.
See also a similar question here Issues with different update date - #2 by janis.plume.
Lauma / firstname.lastname@example.org