I recived official AMD Support note:
Your service request : SR #{ticketno:[8200620930]} has been reviewed and updated.
Response and Service Request History:
Thank you for your response.
Could you please check with game developer for latest game fatch?
It seems that there will be problem with the game and i suugest you to please contact the gamer site for recent fatch.
Thank you.
In order to update this service request, please respond, leaving the service request reference intact.
Best regards,
AMD Global Customer Care
I'm on a intell 4600 / ati 8690m, also without any option to disable the intel card, and had the same annoying problem, but yesterday after I made a clean install of windows 8.1 after having used windows 7, everything works perfectly. Just installed windows, newest intel 4600 driver followed by amd omega driver, then directx and vcredist.
I have no idea why, but the game runs a lot better overall. Perhaps something to do with windows 8.1 having improved directx handling? I dunno, but I'm happy to play the game without any issues.