J'avais le même problème et soumis la question à Daybreak. Voici leur réponse :
-Find your game directory
H1Z1 Just Survive
C:\Program Files (x86)\Steam\Steamapps\Common\H1Z1
H1Z1 King of the Kill
C:\Program Files (x86)\Steam\Steamapps\Common\H1Z1 King of the Kill
-In the window/folder that comes up delete the following files:
H1Z1.exe
LaunchPad.exe
UserOptions.ini
SoundSettings.xml
LoadingScreen.xml
InputProfile_Default.xml
InputProfile_User.xml
vivoxoal_x64.dll
vivoxsdk_x64.dll
-Once these files are deleted, close the H1Z1 window/folder and go back to Steam. Right click on the game in your library and select "Properties", then click on the "Local Files" tab and click "Verify Integrity of Game Cache."
If you have any further issue on this matter, please feel free to reach back out to us.
Regards,
Anthony R.
Technical Support Representative
Daybreak Game Company
En résumé, faut supprimer les fichiers nommés, puis faire une vérification de l'intégralité du cache du jeu.
Pour moi ça a fonctionné