Add support for parameters to Power BI aggregations
Currently, if you'd like to filter a table using a what-if parameter or a disconnected parameter table, this is not supported in Power BI aggregations. This is true even if the parameter table is stored in stored in dual mode, similar to the dimension tables.
Instead, if you try to filter by a parameter, the query will revert to DirectQuery mode and not hit the aggregation tables. See this blog post for more detail.
My understanding is this is currently by design because the parameter value is neither pre-aggregated nor has any mapping.