We’re planning to deploy a hotfix soon to address a bug where the Maiev Shadowsong Hero portrait would show up in Rogue class packs. You should be able to open Rogue packs again after the hotfix is live. This fix will take place on the server side, so you will not see a download.
UPDATE: The hotfix has been deployed and Rogue packs are now unlocked. We’re planning to distribute a full refund of 400 Arcane Dust later today for players who received the Maiev Hero from Rogue Packs, and 1600 Arcane Dust for players who received the Golden version.