We have a new SL64S connected to StudioOne on Mac via USB and Control ethernet. It is currently configured as default input/output for StudioOne. In DAW mode with playback through the board the sound quality degrades, with pops and distortion indicative of a misaligned word clock. The SL64S is set to internal clock, which appears to be correct from the manuals, but we can't find where to sync the clock with the computer.
There is a secondary mixer over AVB and Control, but currently that has been removed to simplify things. When connected it shows a green indicator on the clock source, whereas the clock indicator on the SL64S always stays grey (on both the board and UC Control).
USB is a direct connection, no hubs. Control computer/StudioLive machine is a Mac Pro.