Collectible Card Game Headquarters

Describe the Bug:
When Gravespawn Sovereign ability look for a creature in gy, the game refuse to select one and is stuck forever asking for one

Which card did behave improperly ?
Gravespawn Sovereign

Which update are you using?(date,name)Which type(Duel,Gauntlet,Sealed Deck)
PTT

What exactly should be the correct behavior/interaction ?
When Gravespawn Sovereign ability look for a gy, the game do not refuse to select one

Are any other cards possibly affected by this bug ?
-

Fixed as 27e1555

You can now select a creature from a graveyard, but once you do the game crashes.

Fixed 8bc226c.