I also have this problem on both computer(windows 10) and smart phone(with android). Its insane. Please solve it.
Details: when opening the vault after the finished lifes, the game stucks/freezes (on the rewards part) and you cannot do anything. You close the game and when you come back and enter duels → resume, the game freezes again. And we are stuck on this loop. Big company and not solving serious errors. GJ guys.
Exactly the same problem for me all day today. And you can’t put in a support ticket for anything technical without attaching system files - which aren’t relevant here.
I also have problem on both computers (windows 10 & windows7 pro)
Had this problem since i started a duel round with new character, after 2 games i havent been able to play duel at all. Just getting stuck the second i click resume… 
I have the same problem. And i need to make the 2 lunar quests with duels!
Fix Pls? Wtf Blizzard, not used too this support… I’m stuck allready for atleast a month, maybe longer… WHEN FIX??? WHEN REPLY??
Hello there Blizzard!
After getting a freeze during the end of a duels run (lost after 4 games, 1w3L with the new hero Vanndar) I can no longer enter Duels mode, as it always soft freezes after I press Resume… The game first had a random crash during the game, then after I finished the run, it froze right before the awards. I was able to get my pack, but not the rest of the rewards.
Wish I could provide a video/logs etc, but it does not seem to be an option in these posts.
Please note this is on a PC build.
I am also having the same issue when I click on resume
I have the same problem here. I tried both iphone and PC and they both freeze after I clicked resume
Same thing happened to me. Please fix asap!
same duels are stuck after a losing game. please fix asap i paid for those duels.
Previously, there was a bug with a crash after every second game, now this has also been added. Very disappointed with the technical side of my favorite game.
having the same issues
Same after I lost with DH today and can’t login now 
I had the same issue. Looking closely, you can see a brief flicker of the chest animation behind the screen. As soon as you hit resume, tap the screen in the area where the chest lock would be and it opened for me. A workaround for now…
same problem here, a freeze during the end of a duel run. then lost connection for hrs. when i finally get back on not able to play duels. tried on a different pc and mobile. other modes such as arena, battleground, merc, ranked are ok.
USE THIS FIX: Open hearthstone from android mobile phone. go to duels. click on resume bottom right corner. start spamming clicks near the center of the screen where the drawing is. Dont stop click spamming everywhere around that area until it gives you the rewards. Open the rewards, quit hs from mobile and open from pc. worked for me after a few tries.
Same here. Fix please.
2 weeks without a fix and duel players cant play the game… Blizzard are you jokingg???
Also works to start on iPhone and spam on the portrait then take the rewards.
After that you can log in again on PC and it works.