I've done it sccessfully (and verified via testing) with clients running FMC 6.1 and later. What version are you running? Have you confirmed that your Security Intelligence feed (Objects > Security Intelligence > Network Lists and Feeds > Cisco-Intelligence-Feed) is being updated?
Can you share a screenshot of your Access Control Policy Security Intelligence settings and confirm it is deployed to the device?
Also, if you can, share a connection event showing the allowed connection to a TOR exit node.