No output in UHD - Intensity 4k

Hi

I really need to monitor in 4k on my Avid Symphony, but whenever I switch the project to UHD my UHD monitor goes blank. If I use the conversion within Intensity Pro settings to downscale to HD it pops up again. It all works fine in HD, but screen goes black in UHD.

I've lived with this issue in the past and monitored in HD but I really need this card to output UHD now.

Im using Avid Symphony 2018.12.10

Blackmagic driver 11.1

Its a Samsung UHD 43" momitor that works fine on other HDMI UHD sources.

Thanks

Hi

Do you have an approved cable that can be used for UHD?

Best,
Ole

and you already know that the latest video driver is 11.5.1?