Graphics Card not being used on macOS.

I am using a MacBook Pro (16-inch, 2019) with AMD Radeon Pro 5500M 8 GB, however the GPU is never being used (according to activity monitor).
Within Indesign, the GPU is detected, and the GPU-Performance is enabled.

The performance is really bad and many times the CPU maxes out at 100%, which makes sense because the dedicated GPU is never utilised.

But why? Shouldn't this work?