DXD is just a shorthand for the two common 8x PCM sample rates at 24 bit (24/352,800 and 24/38400), it’s not a different format. The point of DXD lock is to be able to upsample up to 8x while still allowing the upsampler to choose the actual sample rate that that is most appropriate for the incoming stream. That is 352,800 for 44,100 - 176,400 and 384,000 for 48,000 - 192,000.
The DAC will always display the exact rate and bit depth that it is receiving via one of its inputs and in the case you’ve brought up the DAC is receiving 24/384,000 (which is also DXD). If you play a file that is at a 44,100 base frequency then the upsampler will show something like 16/44.1 > DXD and the DAC will show 24/352.8