I understand that you are trying to find the buffer zone inside your polygon using the 'bufferm' function. The 'bufferm' function expects the inputs to be in degrees, specifying the latitude and longitude.
However , In the 'Name_Shifted' mat file, i understand that you have shifted all the points in the 'x' and 'y' direction by a value of 200. when these values are given as input to the 'bufferm' function, it is perceived as latitudes and longitudes. This makes the latitude take values which is much more than 90 degree .This is the reason that the results are not as expected.
You can observe the issue by using 'geoplot' instead of 'plot' for plotting these polygons in the geographic co-ordinates.