I have a Samsung ju6400 and an AMD R9 390. The adapter was working fine and I could do 4k at 60hz. All of a sudden this past week, it can only do 4k at 30hz. The option is completely gone now on the TV. I have all the correct settings that were working previously but this past week I have not gotten 60hz at all when I change it on the display properties. I rolled back to a previous driver as well on the AMD card but that was not the issue. I ended up buying a 2nd cable adapter, but its the same issue with the new one I bought. I have done the whole PC mode and Game mode on the TV settings, and it still does not show 60hz is available. Anyone have any thoughts?