First post, strange problem: I just updated Camera Raw today to the last version. When I open a file (via LightRoom for instance), there is no preview, just a blue square instead, so no way to visualize any changes. However, if I choose to continue with the file in Photoshop, the image is there and Camera Raw is available in the Filters menu, but when I run it, the problem is still there. It did this with both GPU acceleration on and off. The attached picture illustrates this.
Thanks a lot! I thought the problem was related to GPU, but ignored there are separate settings for Camera Raw and only turned it off in PS instead.