It simply does not work, the tool doesn’t even bother storing remaining work for completed cards and their date of completion, as @Roland pointed out, even Microsoft’s own documentation shows 0% completion in their screenshots. And yes, this was reported on MS forums — their response? 'Not a bug.' Apparently, you're just supposed to switch to 'Count of Work Items' because otherwise, it’ll always sit at 0%. My hate for Microsoft grows stronger every day.