So far, the only information I find is this:
"The DNG format is designed for files that you intend to archive or that are going to undergo further post-processing with DNG-compatible software such as Adobe Camera Raw/Photoshop/Lightroom.
The DNG generated by DxO OpticsPro is a 16-bit linear DNG format, which is only available for original images shot in RAW. With linear DNG, the three color channels have been individually calculated, which means that the file is three times larger than the original RAW file. This format offers the same advantages of reversibility as with a camera-generated RAW file."
DXO help says this:
The exported DNG are linear DNG, not CFA DNG
your program may not support that
they are exported specifically for use with Adobe softwares
...
That makes sense
it thinks it's a RAW DNG but it's demosaiced
OpticsPro itself won't even take the image again