With the Olympus OM-D E-M5 II, a high resolution RAW (64 MP instead of 16) generates a *.ORF file of 64 megapixels and a *.ORI file of 16 megapixels.
The *.ORI file is a "normal" RAW file, but with a different extension to differentiate it from the high-resolution RAW file. The "normal" RAWs usually have .ORF extension, so the .ORI extension is not recognized by DxO PhotoLab 3.
We plan to add support for the .ORI extension in future DxO PhotoLab 3 updates. For now, you'll need to rename the files ending in .ORI to .ORF before you can view and process them in DxO PhotoLab 3.