Just upgraded to High Sierra on MacPro laptop. Cannot use my NIK filters. Also when I opened my first finished Jpeg in PS CC 2018, it opened at a reduced size like 2x3. I my photos are saved as 8x10 or 4x5. Never had these problems before. All help would be appreciated. Thanks!
I don't know if this will help with the NIK filters. ( have not actually watched it, but it professes to tell you how to install NIK with CC2018
Regarding your image size, are you saying that you are losing pixels, or that the DPI is different? Does the image size relate to Preference settings by any chance? If you are losing pixels, that's a really big deal. If just the DPI then not so much so.