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.

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.