ICS-43434 23 or 22 bits?

According to the data sheet the result is I2S, signed 24-bit (+/-23 bit). Please look at the attached screenshot.
- The first bit is idle as per the data sheet, marked in green. OK.
- The 2nd bit is the sign-bit (MSB), marked in orange. OK.
- Bits 3..25 are supposed to be the 23 data bits following the sign-bit, but there is never a "1" at the position 25. I put the oscilloscope in persistent mode and let it run.
In the data sheet bit 25 is marked correctly as LSB, as it should contain data. Should I just take it as 0 and I'll have +/-23 bits where the last bit is always 0, or the LSB is in fact the 22th and the result is +/-22 bits?