It seems the Lumin is not seeing the USB DAC.
Please try these separately:
1. Use a different USB cable, especially an ordinary (i.e. non-audiophile) USB printer cable. Double check that you have turned off USB custom resampling in Lumin app.
2. Disconnect the USB cable from Lumin. Plug in a USB thumb drive in FAT32 or NTFS format with some 44.1kHz music files into the Lumin. Wait for 10 seconds. In Lumin app, see if there is a Lumin USB Music Server entry in the library selection. Choose it as the library. Set Lumin X1 output back to analog. Add a 44.1kHz music file from the USB drive to the current playlist. then play it. If this works, it proves your Lumin USB port hardware is not faulty.
3. Please use a computer to connect to the USB DAC and play something using any computer audio software. See if the DAC USB hardware is operating normally.
4. Alternatively, you may use a 1.5m BNC to RCA 75 ohm coaxial cable to connect the Lumin BNC port to the DAC SPDIF port. In Lumin app, set output to SPDIF. Then set SPDIF resampling: DSD to 176.4kHz.
There should not be a USB compatibility issue, because a reviewer specifically tested Lumin USB output to this DAC.