I'm using a Z390 Designare (F6c Firmware) motherboard with an i9 9900K CPU and G.Skill 2x16GB 3200MHz RAM. I tried to connect a Thunderbolt 1 audio interface (Universal Audio Apollo Quad with TB1 card) via a Startech Thunderbolt 3 to Thunderbolt adapter and the Apple Thunderbolt 3 Adapter without any success. I enabled Discrete Thunderbolt and I put the security level to "no security" yet the motherboard doesn't recognize this audio interface.
It is probably the motherboard's fault (probably BIOS), since it is not able to localize the audio interface under the very latest Windows 10 Pro with the newest Thunderbolt drivers or the newest Mac OS X Mojave 10.14.2 .
Both adapters, the audio interface and the thunderbolt 1 cable are working correctly. I tested them on my 2017 MacBook Pro (Mojave OS) with Alpine Ridge Thunderbolt 3 ports, and there I was able to use the audio interface with both adapters. I don't think that Intel is at fault here, either. Their Thunderbolt protocol allows for backwards-compatibility with both Thunderbolt 1 and 2 devices, and this also holds true for Titan Ridge Thunderbolt 3, so there must be something wrong with Gigabyte's implementation of the Thunderbolt 3 ports and the way they react to the board's BIOS.
Will Gigabyte fix this problem with a new BIOS update or is this issue irreparable (a hardware misconstruction)?