Looks like PhotoLab 6.6.0 Elite does not support Sony Pixel Shift ARQ files.
As a work-around I converted the pixel shift files to a single DNG using “PixelShift to DNG” BUT then I lose the ability to take advantage of the DxO lens distortion correction - it is grayed out! (It works on a single .ARW file).
I did notice that when I rolled over the DNG in PhotoLab Photo Library there is a notice attached to the file: “DxO Optics Module: Some corrections are not available on Linear DNG diles.” Perhaps that is one of the limitations?
Typically, DNG files store unprocessed RAW data.
By contrast, Linear DNG files store some intermediate results of RAW conversion.
Some initial processing steps have been applied — but only linear ones.
This means that none of the data is lost to one-way, non-linear processes.
As a result, Linear DNGs have exactly the same flexibility as RAW files when it comes to editing aspects such as brightness, color, and contrast.
The last sentence mentions the flexibility “when it comes to editing aspects such as brightness, color, and contrast.” Alas, PhotoLab’s key features are not available.
if you want OEM optics correction ( provided by Sony ) and then to work with the linear DNG in DxO PL6 you need to use Iridient S-Transformer instead of “PixelShift to DNG"… Iridient S-Transformer will apply embedded optics correction when generating a linear DNG file ( there are options what do you want to apply - see screenshot) - so at least this is a work around…