Hi @Black_Pen_Mathematic
Welcome to eazyBI community!
There is an option on how you can pass down the Parent custom field value to Sub-tasks. It is limited to any Single value dimensions and values only (not the history).
You can use update_from_issue_key as an additional parameter in advanced settings for passing down the custom field value. We suggest creating a new calculated JavaScript custom field to copy the value from the original field, and then use it instead.
Please check out community post an example: Aggregate story points on stories under a epics grouped by a custom attribute
Only, in your case, as you do not use Epic link, but Parent - Sub-task link for passing down the value, use update_from_issue_key="parent_issue_key" (not “epic_key” as in the example).
After importing this field as a dimension, use it in reports as any other custom field that has values in all level issues.
Best,
Ilze / support@eazybi.com