Rockstar Games has temporarily disabled the Diamond Casino Heist in GTA Online for PC players. The reason for such drastic measures was a serious exploit. The studio's technical support reported the following: “We have made a temporary change to GTA Online on PC to protect players from an identified vulnerability. GTA Online PC players will not be able to access Casino Heists or setup the Arcade Property until a permanent fix is in place."
According to data miner TezFunz2, the exploit allowed the attackers to gain full control over the accounts of at least three PC players. Rockstar Games is currently working to fix the vulnerability. Restoration of access will be announced later. Let us remind you that the Steam version of Grand Theft Auto 4 recently received a new patch.