The DNG files DxO OpticsPro creates are only meant to be used as intermediate files for further processing in other applications. Additionally, some corrections have been applied in a non-reversible fashion, such as demosaicing, noise reduction, etc.
DNG files created by DxO OpticsPro are not equivalent to the original RAW files, and for this reason, you should not consider OpticsPro as a DNG converter. It only makes sense to produce DNG files with OpticsPro if you wish to use these files in another program other than DxO OpticsPro.
If you want to return and continue working on an image you exported from DxO OpticsPro, we strongly recommend that you use the original RAW file and its .dop (sidecar) file, which remembers the initial settings you used to process the image.