Help you a great god:
Macbook pro 2014, MacOs 10.15.5 Catalina, lightning 2 interface lightning 3, external Core X ray snake, built-in AMD Radeon hd 64 Vx Vega graphics card, in the process of connecting try closing the SIP, and run PurgeWrangler script, graphics, dock can identify the graphics card can't identify, however, the lack of drive, turn to experienced great god help,