W4100 GPU Resolution Issue?

I have a w4100 and can't get it to display higher than 1080p on an  LG 29UM57-P native res 2560 x 1080.  I am using a mini dp to hdmi converter. What do I need to do for this to work? The other screens are 2 mini dp to vga and 1 mini dp to hdmi at 1080p, all those work fine.