See this screenshot: http://i.imgur.com/Wia6xSn.jpg It's a 400% close-up of an .orf raw file. Note the indicated area (and elsewhere) where 2x2 pixels are nearly the same colour and produce blocking artifacts. Lightroom version is 6.6, image was only imported with no additional adjustments.
Edit: Capture One and Olympus Viewer don't have the same problem. Here's a screenshot from Olympus Viewer: http://i.imgur.com/n3QXKJl.png
Are you an Adobe employee or connected to the Lightroom team? I imagine
they have access to this or a similar type of camera, or at least some
raw files. Otherwise I could try to take some photos that contain
similar problems, but without personal elements.
I am not an Adobe employee, but I can pass along information to Adobe people, which is one reason I asked for a sample image, and I know from experience if I try to pass something along to them and don't have an example image they will ask for one.