Hello @ACvitus,
This is due to the fact that the Vitus is not Roon Ready certified. In its current state, the Vitus is reporting to Roon that it does not support DSD playback, so Roon will not play DSD content to the device under any circumstance. This is something that is checked during the Roon Ready certification process to ensure that all supported formats play correctly from Roon.
Roon will allow you to override the DSD settings for USB DACs, as these devices are not “certified” in the same way that Roon Ready devices are.
-John