Thunderbolt 3 with threadripper on a Asrock x399 fatality motherboard. Help needed.  

@i0ntempest, I have no use for USB 2.0 through the TB3 AIC at all so I never tested it. Motherboards have plenty of USB-A ports so I did not want to complicate this Thunderbolt 3 workaround with more connections.

I have a AMD Epyc 7302 (16-core) and a ASRock RomeD8-2T. I installed the Gigabyte Titan Ridge AIC TB3 card, shorted out the pins on the header cable, and connected the USB2 header to a "real" USB port using an adapter cable. The card APPEARS to be working, with no driver errors in windows and it even recognizes my TB3-only nvme SSD enclosure. While the thunderbolt control center recognizes the enclosure and I can approve the device, the drive does not show up in Windows anywhere. I confirmed the drive and enclosure work just fine on a laptop. Same for my Razer Core X. Thunderbolt control center recognizes and approves it, but no new display adapters appear. No errors, either. 

This is the adapter cable I used, since there isn't a USB2 header on this motherboard:

https://www.amazon.com/gp/product/B07Q4QZW57/

Any ideas? 

@dregpu, Have you tried cold-boot with the TB3 device connected following Thunderbolt detection?

@itsage, Yes, no change with cold boot. The only other thing I can think of, is that this motherboard wants the TB3 AIC in slot 1, but that is not where I installed it. I figured since I wasn't using the TB3 header on the motherboard it wouldn't matter. Perhaps it does?

@dregpu, Each motherboard behave differently with the AIC in my experience. In my X399M Taichi, the bottom PCIe slot works best. I've tried other slots which worked but the AIC would randomly become undetected.