2019 15" MacBook Pro (RP555X) [9th, 6C, H] + RX 5700 XT @ 32Gbps-TB3 (AKiTiO Node) + macOS 10.15.3 & Win10 1909 [moltentofu]
Thank you for sharing! I followed the same steps, however I did it with the latest Windows insiders build, latest version of all drivers, and Catalina 10.15.3 beta 2.
After step 18, instead of getting error 12 resolved, the 5700 XT stops being recognized and instead is showing up as a "PCI Express Downstream Switch Port" (status: Code 12).
Any help would be appreciated.