I matched the exact amixer config from thread 367599 (Sample Rate 48000, BCLK Ratio 64, cbs-cfs, i2s, S32_LE); the stream runs OK but BCLK (pin 12), FS (pin 35) and DOUT (pin 40) are all still Low on the scope*, while the same pads drive 3.3 V driven as GPIO outputs. *
So this doesn’t seem to be amixer config or the TXB0108 translator, my guess is the SoC pad isn’t driving in i2s2/SFIO mode on L4T R39.2