My device is Macbook Pro 13 2018(with Catalina) and my egpu is a Vega56. I've followed the instructions here https://kb.parallels.com/124266. As it says in the instruction, I enable the option 'Prefer External GPU' and then restart the Parallels Desktop. However, when I run some benchmarks or play games, the performance is rather poor. And as I can see in my iStat monitor, the egpu is not working at all. So I wanna know where the problem is.