Ben, I had the exact same issues you are describing for some time and posted it on the Adobe forums directly about a year ago. Everyone said I had a display calibration issue too, even though everything else worked and displayed fine. How one file type (I reported problems with TIF images) can be related to a display calibration issue is beyond me.
I tracked down the problem to the size of the TIF file in pixel dimensions. If the images are too large (many of my stitched images had this problem), then ACR will display the image improperly. My workaround is to create a downsized copy of the image, change the ACR settings to my liking and click done. Now all you have to do is copy the settings from this "proxy" image to the real one. Now you can open the "real" image in ACR and simply click "Open Object" without making any changes.
It will open in PS correctly with all the changes you made on the "proxy" image.
I hope this makes sense. BTW, I never did figure out the exact dimensions that caused ACR to break, but I'm guessing somewhere between 10-15K on one side.
Hopefully this is causing your issue too.