Usually the xmp files are in the same folder as the images.
They would be named the same as the document file name followed by the xmp extension.
Look at your camera raw preferences and see what your Save image settings in is set to.
The side car xmp files are only for camera raw files and not jpegs or tifs.
Also, in camera raw, you can go to the flyout menu and select Camera Raw Defaults to reset the settings on an open camera raw file.