The new Gen5 USB board in my Yggdrasil Dac works in exclusive mode without problems.
But I had problems when I received the Schiit Eitr ( Gen5 Usb to Coax switcher). Never got it working with Roon in exclusive mode.
Finally it got replaced by Schiit. That was the solution. Now it does work as intended in exclusive mode.
What I want to say: Also consider the possibility that you received a faulty USBGen5 board in your Yggdrasil that needs to be replaced by Schiit Audio.