Ability to report on multiple Metrics owners

We have a bunch of Metrics scorecards set up in multiple workspaces. 

What I am looking for is a single report that shows everyone who is a metric owner (that is, the names appearing in the "Assigned To" column), by scorecard, so that when someone leaves I can easily check if they were responsible for updating any metrics, and I can then transfer them over to someone else.

This would also be very useful when we want to send out reminders to people to update their metrics in a particular scorecard.

I can currently do a Power BI report on a single scorecard, but that only shows the first assigned person - not very helpful if a metric has more than one person assigned to it.