FFXIV doesn't use the GPU for shadows either. It's common for parts of it to not use the GPU.
If you have an NVIDIA+Intel hybrid set-up, it will always show it using the intel GPU/CPU. Disabling the intel GPU/CPU via the BIOS will actually disable the NVIDIA GPU in that case. (Yes, I've done this before.)
The only option is to use the appropriate control panel (AMD/NVIDIA) to tell the GPU to not have PSO2 use the onboard graphics. By default, 3D Settings in both AMD/NVIDIA are set to "auto select." You should change this to use the dedicated card instead:
You may need to restart the computer after doing this change.