The manual of your DAC actually states “The USB 2.0 input receives a 24-48kHz data stream”. It also states it’s using a CM-108 USB chip, which really is limited to 48kHz according to the C-media manufacturer specs.
You need to try the coaxial input for Hi-Res sample rates. I think the Nucleus does not have a coaxial output, so you may consider upgrading your equipment. Better yet, get a Roon Ready player.