After choosing a 10-bit per channel graphics card (AMD Radeon Pro / Nvidia Quadro), and connecting it to a 10-bit per channel monitor, there is a setting in Photoshop you should enable to create a 30 bit workflow.
Setting Graphics Card Software to Display 10-bit Output
After choosing a 10-bit per channel graphics card (AMD Radeon Pro / Nvidia Quadro), and connecting it to a 10-bit monitor, you will want to make sure the graphics card is set to display 10 bit output in its software.
