The upsampling does not occur if using the CXN to pass the digital stream on to another DAC, it is only done when it is being used as the DAC and doing the conversion to analog.
From their website:
Upsampling only occurs when using analogue outputs as the process is implemented within the digital to analogue conversion process.
However, the CXN seems always report this upsampling to Roon whether it is doing so or not.
See this thread: