Problem with GetPixel from a resized texture in 5.4

Hey I just updated to Unity 5.4 but now GetPixel is having trouble getting clean colour values from a texture that is resized in the import settings. (It used to work fine of course)

I'm importing the texture and reducing it from 1024x1024 to 256x256 with all the usual settings to give pixel perfect resizes like sampling bypass, point filter, truecolor, no mipmaps. But I'm now getting colour values like the image is bilinear filtered.

If I resize the image to 256 in Photoshop before it gets to Unity, the colour values work perfectly. But I need the images to be 1024 on the hdd and 256 in the import settings.

Anyone got any ideas of what's going on?