You have to wait until mclk is stable before reply on the USB Bus. What we saw on the board (on the oscilloscope) was no or a wrong MCLK Signal. So "AudioHwConfig" should only return if the MCLK is stable. It is a good idea to place test pads for eg. MCLK, PLL Sync, 3,3V 1,0V etc.
Another trick is to ad a resistor in the master clock line so you can check with different values e.g. 33 Ohm if the signal gets more solid.
To increase "AUDIO_PLL_LOCK_DELAY" is only a hack, which might help in some cases. By the way the USB standard needs a reply within 1 second so you must not increase AUDIO_PLL_LOCK_DELAY to much.
I assume you have an issue with the MCLK try to measure is on the board.
- Which PLL are you using?
- does it generate the right frequencies?
- are the DAC and DAC configured right?