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In this case, you could try creating new user-defined calculated measure (with decimal format) to calcualte results only for issues created since Sep 1 2021
[Measures].[Issue created date],
'Sep 1 2021', 'today'
[Measures].[Average days in transition status]>0
[Measures].[Average days in transition status]
When selecting it in the report, please make sure you enable “Nonempty” cross join for report rows (image below)
I used these advanced settings to define the field in my example (see image below)
name = "Created since Sep 1 2021"
data_type = "string"
dimension = true
var zbpStartDate = new Date(2021, 8, 1);
issue.fields.customfield_crsince1Sep2021 = new String(Date.parse(issue.fields.created) >= zbpStartDate);
One more solution would be using JQL filter to skip older issues from import
But that approach would affect all reports on your eazyBI account
Martins / eazyBI