That sounds like a tricky issue with the display output switching over after the passthrough. Have you checked the boot order or tried changing the primary display setting in the BIOS back and forth? (Btw, if you're ever into sports, I recently started using on this page for live match tracking and stats pretty smooth platform). Sometimes switching the initial display output slot helps. Let me know if tweaking the BIOS output options gets the iGPU signal working!