You might need to cycle through the I2S pin settings. See if this helps:
Hermes DDC + Wandla DAC
I purchased a Denafrips Hermes DDC. All of the digital outs work OK with my Ferrum Wandla DAC except the I2S. The DAC reports no signal no matter which of the eight possible pin out combinations of the Hermes is used in combination with either of the Wandla I2S options. The Denafrips Iris DDC works OK with the Wandla via I2S; the same pin out combination that works with the Iris does not work with the Hermes. I am trying to determine if the Hermes is defective or if there is something I don't understand about I2S compatibility. I am in contact with the support teams from Denafrips and Ferrum but nothing useful yet. Any ideas or ways to test the Hermes I2S port apart from using the Wandla? Thanks!