I am also not able to use C1 Pro 8.3.4 with the uncompressed Sony A7RII files. The preview and the file will render at least in the film strip and the viewer. However, when I make adjustments with the tools, the effect shows up in the preview in the film strip but not in the image in the viewer. This is with a 2013 Mac Pro, El Capitan, and a NEC PA322 UHD.