Can't check with Mavericks because I'm still on 10.8.5, however I can't say I heard this behavior before.
Can you select a file that is changed with -0.95 but does not show the result and with right mouse click menu choose purge cache for selection, does that make a difference?
What version of Camera Raw are you using and What Canon are you using.
Purging chace does'n make any change. The problem is that Exposure value saved in .XMP file is 0 - this is the following line in the .XMP file as I guess:
So it is Bridge / Camera RAW error in writing correct data into .XMP
The version of camera RAW is 8.3, my camera is 5D Mk III.