DE1-SoC: Problem with audio core for Altera DE-Series Boards in Avalon ST mode

Are you sure the codec was actually function like you thought? I reproduced your work (Using the 50 Mhz clock) and used a logic analyzer directly against the pins of the Wolfsom chip, and found that there were no clock signals being produced, it seems that the codec went into line-in by pass mode. The only pins that were producing any sort of signal were the analog in and analog out pins.