Fusion
I experience the same issue. An eGPU-SONNET eGFX Breakaway Box 550 with a Gigabyte Radeon RX Vega 56 is connected to a Thunderbolt 3 port of my Mac mini. In the Fusion 360 application Info window I checked "Prefer External GPU" option. In the Graphics Diagnostics module of Fusion 360 however the internal Intel UHD Graphics of my Mac mini is listed but the available GPU RAM which is listed is that of the external videocard. Also, I'm pretty sure that a few days ago the external Radeon GPU was listed in the graphics diagnostics. But that's not the case anymore now. I'm wondering if Fusion 360 is supporting an external GPU and if the graphics performance of the GPU is having a substantial influence to the performance of Fusion? The GPU History window of Activity monitor ( Window > GPU History ) is hardly showing any visible response of the External videocard while rendering an object. If I don't check the "Prefer External GPU" option the Intel UHD video isn't showing any response at all. Instead all 6 cores of the CPU are stretched to the limit and the rendering process is using up more than 1000% CPU. In both cases the Graphics Diagnostics of Fusion are displaying the Intel UHD as the active graphics card and the RAM size of the external GPU.
Mac mini 2018 - 3,2 GHz 6-Core Intel Core i7 - 16GB RAM - Apple 512GB SSD
eGPU-SONNET eGFX Breakaway Box 550 and Gigabyte Radeon RX Vega 56
Fusion 360 product version 2.0.7029
