Hi @Mickael,
If I understand you right, you have a customfield on the Epic level but want to see the stories and other children of that Epic filtered by the field of Epic.
Generally, the page filter applies to measures, and the measures come from the lowest levels of the hierarchy.
In order to apply a filter to fields at higher hierarchy levels, you need to inherit the values of those fields also to the child issues.
Some standard fields could be inherited as isuse link field dimensions. Please read more about that here -Issue link field dimensions.
However, customfields require a slightly different approach. They should be “inherited” during the data import using JavaScript-calculated fields.
Please read more about that here - Epic level custom field.
Regards,
Oskars / support@eazyBI.com