What is it supposed to look like? What GPU rendering are they turning on and off? Does it happen on both Macs and PCs? Does it happen on CUDA, OpenCL, or Metal or all or both?
Don't forget, you can download a trial of CC 2017 and try it out for yourself and maybe make a version that works with GPU-acceleration.
It's suppose to look like a plain, normal image without the tiling/offset in the middle.
In the Project Settings, there's an option for gpu rendering or software rendering. Switching back and forth changes what the preview looks like, even though the values of the offset effect aren't changing.
I'm not sure about mac or pc, but from a few comments I've seen, I think it's mostly happening on PCs.
Not sure about CUDA, OpenCL, or Metal either.
Point is, whether its Mac or PC, the preset is just a combination of effects and should work the same.
With GPU rendering on or off, the same values in the offset effect should give you the same result, but it doesnt for some reason.
Doesn't make sense to me.
Are you still facing this problem? If not, let us know how you solved it. If so, please let us know so we can assist you further.