Atlus have released a new patch for Persona 4: Arena
that fixes a number of different issues with the game.
As well as general game balance and network issues, the patch aims to fix a glitched achievement that was unobtainable for some players:
A glitch that caused Yukiko's Fire Break Agidyne attack to become unblockable has also been fixed.
The patch is available to download now when you load up the game.