The Host LED is white.
Stays white when I set the UFX+ from Auto to TB.

In the meantime I also reflashed the latest TB controller firmware. Symptoms still look the same.

The files referenced in rme_pcie.inf aren’t copied where the inf file says they should be, though I expect this would occur automatically when Windows recognizes the device and loads the driver?

The TB app asked permission for the UFX+, which I set to always grant.
The TB controller is set to security ‘user auth’ by default. I tested with security disabled, as well. No dice.
Any specific controller features/settings required?

Bios settings for the Asus TB EX3 controller (current settings in cursive):

• TB USB Support on

• TB Boot Support off

• Wake from TB Devices off

• TB PCIe Cache-line Size 32

• GPIO3 Force Pwr on

• Wait time after applying force pwr 200ms

• Skip PCI Option Rom enabled

• Security Level SL1 user auth

• Reserve (minium available) mem per phy slot 32

• Reserve (minimum available) P mem per phy slot 32

• Reserve IO per phy slot 4

• Delay before SX exit 300

• GPIO filter on

• Enable CLK req fot devices off

• Enable ASPM for devices off

• Enable LTR/Latency Tolerance Reporting off

• Extra Bus Reserved 65

• Reserved Memory for root bridge 386

• Memory Alignment 26bits

• Reserved PMemory 960

• PMemory Alignment 28

• Reserved I/O 0

• Alpine Ridge XHCI WA off